diff --git a/10/20/m1020.swift b/10/20/m1020.swift
new file mode 100644
index 0000000..b3d5a50
--- /dev/null
+++ b/10/20/m1020.swift
@@ -0,0 +1,53 @@
+// Solved:
+// (M) Number of Enclaves
+// https://leetcode.com/problems/number-of-enclaves/
+
+class Solution {
+	typealias Coord = (x: Int, y: Int)
+	
+	private func _processEnclave(_ grid: inout [[Int]], _ x: Int, _ y: Int) -> Int {
+		let xmax = grid.count - 1, ymax = grid[0].count - 1
+		var tile: [Coord] = [(x, y)]
+		var nEnclave = 0
+		
+		grid[x][y] = 0
+		while !tile.isEmpty {
+			let c = tile.removeLast()
+			// If the tile is on bound, this is not an enclave
+			if c.x == 0 || c.y == 0 || c.x == xmax || c.y == ymax { nEnclave = -1 }
+			if nEnclave >= 0 { nEnclave += 1 }
+			if c.x > 0 && grid[c.x - 1][c.y] == 1 { grid[c.x - 1][c.y] = 0; tile.append((c.x - 1, c.y)) }
+			if c.y > 0 && grid[c.x][c.y - 1] == 1 { grid[c.x][c.y - 1] = 0; tile.append((c.x, c.y - 1)) }
+			if c.x < xmax && grid[c.x + 1][c.y] == 1 { grid[c.x + 1][c.y] = 0; tile.append((c.x + 1, c.y)) }
+			if c.y < ymax && grid[c.x][c.y + 1] == 1 { grid[c.x][c.y + 1] = 0; tile.append((c.x, c.y + 1)) }
+		}
+		
+		return nEnclave > 0 ? nEnclave : 0
+	}
+	
+	func numEnclaves(_ grid: [[Int]]) -> Int {
+		var g = grid
+		var res = 0
+		
+		// Obvious case - no inner tiles at all
+		if g.count <= 2 || g[0].count <= 2 { return 0 }
+		
+		for i in 1..<g.count - 1 {
+			for j in 1..<g[0].count - 1 {
+				if g[i][j] == 1 {
+					res += _processEnclave(&g, i, j)
+				}
+			}
+		}
+		
+		return res
+	}
+}
+
+func _main() {
+	let x = Solution()
+	// Must be 3
+	print(x.numEnclaves([[0,0,0,0],[1,0,1,0],[0,1,1,0],[0,0,0,0]]))
+	// Must be 27
+	print(x.numEnclaves([[0,0,0,1,1,1,0,1,1,1,1,1,0,0,0],[1,1,1,1,0,0,0,1,1,0,0,0,1,1,1],[1,1,1,0,0,1,0,1,1,1,0,0,0,1,1],[1,1,0,1,0,1,1,0,0,0,1,1,0,1,0],[1,1,1,1,0,0,0,1,1,1,0,0,0,1,1],[1,0,1,1,0,0,1,1,1,1,1,1,0,0,0],[0,1,0,0,1,1,1,1,0,0,1,1,1,0,0],[0,0,1,0,0,0,0,1,1,0,0,1,0,0,0],[1,0,1,0,0,1,0,0,0,0,0,0,1,0,1],[1,1,1,0,1,0,1,0,1,1,1,0,0,1,0]]))
+}
diff --git a/docs/index.md b/docs/index.md
index 0c93567..338af71 100644
--- a/docs/index.md
+++ b/docs/index.md
@@ -1,148 +1,149 @@
-Here is the list of solved problems. Language images are clickable and lead to the solution file.
-
-| No.  | Description (link to Leetcode)                                                                                                                                    | Explanation |               Lang               |
-|:----:|-------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------|:--------------------------------:|
-| 2 | ![M](img/M.png) [Add Two Numbers](https://leetcode.com/problems/add-two-numbers/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/02/m2.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 3 | ![M](img/M.png) [Longest Substring Without Repeating Characters](https://leetcode.com/problems/longest-substring-without-repeating-characters/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/03/m3.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 5 | ![M](img/M.png) [Longest Palindromic Substring](https://leetcode.com/problems/longest-palindromic-substring/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/05/m5.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 7 | ![M](img/M.png) [Reverse Integer](https://leetcode.com/problems/reverse-integer/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/07/m7.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 13 | ![E](img/E.png) [Roman to Integer](https://leetcode.com/problems/roman-to-integer/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/13/m13.py" target="_blank"><img src="img/py.png"></a> |
-| 25 | ![H](img/H.png) [Reverse Nodes in k-Group](https://leetcode.com/problems/reverse-nodes-in-k-group/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/25/m25.py" target="_blank"><img src="img/py.png"></a> |
-| 30 | ![H](img/H.png) [Substring with Concatenation of All Words](https://leetcode.com/problems/substring-with-concatenation-of-all-words/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/30/m30.py" target="_blank"><img src="img/py.png"></a> |
-| 33 | ![M](img/M.png) [Search in Rotated Sorted Array](https://leetcode.com/problems/search-in-rotated-sorted-array/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/33/m33.py" target="_blank"><img src="img/py.png"></a> |
-| 34 | ![M](img/M.png) [Find First and Last Position of Element in Sorted Array](https://leetcode.com/problems/find-first-and-last-position-of-element-in-sorted-array/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/34/m34.py" target="_blank"><img src="img/py.png"></a> <a href="https://github.com/chemandante/leetcode/blob/master/00/34/m34.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 35 | ![E](img/E.png) [Search Insert Position](https://leetcode.com/problems/search-insert-position/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/35/m35.py" target="_blank"><img src="img/py.png"></a> |
-| 41 | ![H](img/H.png) [First Missing Positive](https://leetcode.com/problems/first-missing-positive/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/41/m41.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 50 | ![M](img/M.png) [Pow(x, n)](https://leetcode.com/problems/powx-n/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/50/m50.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 60 | ![H](img/H.png) [Permutation Sequence](https://leetcode.com/problems/permutation-sequence/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/60/m60.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 62 | ![M](img/M.png) [Unique Paths](https://leetcode.com/problems/unique-paths/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/62/m62.py" target="_blank"><img src="img/py.png"></a> |
-| 67 | ![E](img/E.png) [Add Binary](https://leetcode.com/problems/add-binary/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/67/m67.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 69 | ![E](img/E.png) [Sqrt(x)](https://leetcode.com/problems/sqrtx/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/69/m69.py" target="_blank"><img src="img/py.png"></a> <a href="https://github.com/chemandante/leetcode/blob/master/00/69/m69.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 74 | ![M](img/M.png) [Search a 2D Matrix](https://leetcode.com/problems/search-a-2d-matrix/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/74/m74.py" target="_blank"><img src="img/py.png"></a> <a href="https://github.com/chemandante/leetcode/blob/master/00/74/m74.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 86 | ![M](img/M.png) [Partition List](https://leetcode.com/problems/partition-list/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/86/m86.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 88 | ![E](img/E.png) [Merge Sorted Array](https://leetcode.com/problems/merge-sorted-array/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/88/m88.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 89 | ![M](img/M.png) [Gray Code](https://leetcode.com/problems/gray-code/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/89/m89.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 92 | ![M](img/M.png) [Reverse Linked List II](https://leetcode.com/problems/reverse-linked-list-ii/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/92/m92.py" target="_blank"><img src="img/py.png"></a> |
-| 102 | ![M](img/M.png) [Binary Tree Level Order Traversal](https://leetcode.com/problems/binary-tree-level-order-traversal/) | | <a href="https://github.com/chemandante/leetcode/blob/master/01/02/m102.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 114 | ![M](img/M.png) [Flatten Binary Tree to Linked List](https://leetcode.com/problems/flatten-binary-tree-to-linked-list/) | | <a href="https://github.com/chemandante/leetcode/blob/master/01/14/m114.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 118 | ![E](img/E.png) [Pascal's Triangle](https://leetcode.com/problems/pascals-triangle/) | | <a href="https://github.com/chemandante/leetcode/blob/master/01/18/m118.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 119 | ![E](img/E.png) [Pascal's Triangle II](https://leetcode.com/problems/pascals-triangle-ii/) | | <a href="https://github.com/chemandante/leetcode/blob/master/01/19/m119.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 136 | ![E](img/E.png) [Single Number](https://leetcode.com/problems/single-number/) | | <a href="https://github.com/chemandante/leetcode/blob/master/01/36/m136_x64.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 137 | ![M](img/M.png) [Single Number II](https://leetcode.com/problems/single-number-ii/) | | <a href="https://github.com/chemandante/leetcode/blob/master/01/37/m137.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 153 | ![M](img/M.png) [Find Minimum in Rotated Sorted Array](https://leetcode.com/problems/find-minimum-in-rotated-sorted-array/) | | <a href="https://github.com/chemandante/leetcode/blob/master/01/53/m153.swift" target="_blank"><img src="img/sw.png"></a> |
-| 167 | ![M](img/M.png) [Two Sum II - Input Array Is Sorted](https://leetcode.com/problems/two-sum-ii-input-array-is-sorted/) | | <a href="https://github.com/chemandante/leetcode/blob/master/01/67/m167.swift" target="_blank"><img src="img/sw.png"></a> <a href="https://github.com/chemandante/leetcode/blob/master/01/67/m167.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 172 | ![M](img/M.png) [Factorial Trailing Zeroes](https://leetcode.com/problems/factorial-trailing-zeroes/) | | <a href="https://github.com/chemandante/leetcode/blob/master/01/72/m172.py" target="_blank"><img src="img/py.png"></a> <a href="https://github.com/chemandante/leetcode/blob/master/01/72/m172.swift" target="_blank"><img src="img/sw.png"></a> |
-| 200 | ![M](img/M.png) [Number of Islands](https://leetcode.com/problems/number-of-islands/) | | <a href="https://github.com/chemandante/leetcode/blob/master/02/00/m200.py" target="_blank"><img src="img/py.png"></a> |
-| 202 | ![E](img/E.png) [Happy Number](https://leetcode.com/problems/happy-number/) | | <a href="https://github.com/chemandante/leetcode/blob/master/02/02/m202.py" target="_blank"><img src="img/py.png"></a> |
-| 204 | ![M](img/M.png) [Count Primes](https://leetcode.com/problems/count-primes/) | | <a href="https://github.com/chemandante/leetcode/blob/master/02/04/m204.py" target="_blank"><img src="img/py.png"></a> <a href="https://github.com/chemandante/leetcode/blob/master/02/04/m204.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 206 | ![E](img/E.png) [Reverse Linked List](https://leetcode.com/problems/reverse-linked-list/) | | <a href="https://github.com/chemandante/leetcode/blob/master/02/06/m206.py" target="_blank"><img src="img/py.png"></a> |
-| 215 | ![M](img/M.png) [Kth Largest Element in an Array](https://leetcode.com/problems/kth-largest-element-in-an-array/) | | <a href="https://github.com/chemandante/leetcode/blob/master/02/15/m215.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 234 | ![E](img/E.png) [Palindrome Linked List](https://leetcode.com/problems/palindrome-linked-list/) | | <a href="https://github.com/chemandante/leetcode/blob/master/02/34/m234.py" target="_blank"><img src="img/py.png"></a> |
-| 235 | ![E](img/E.png) [Lowest Common Ancestor of a Binary Search Tree](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-search-tree/) | | <a href="https://github.com/chemandante/leetcode/blob/master/02/35/m235.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 236 | ![M](img/M.png) [Lowest Common Ancestor of a Binary Tree](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree/) | | <a href="https://github.com/chemandante/leetcode/blob/master/02/36/m236.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 240 | ![M](img/M.png) [Search a 2D Matrix II](https://leetcode.com/problems/search-a-2d-matrix-ii/) | | <a href="https://github.com/chemandante/leetcode/blob/master/02/40/m240.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 242 | ![E](img/E.png) [Valid Anagram](https://leetcode.com/problems/valid-anagram/) | | <a href="https://github.com/chemandante/leetcode/blob/master/02/42/m242.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 260 | ![M](img/M.png) [Single Number III](https://leetcode.com/problems/single-number-iii/) | | <a href="https://github.com/chemandante/leetcode/blob/master/02/60/m260.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 263 | ![E](img/E.png) [Ugly Number](https://leetcode.com/problems/ugly-number/) | | <a href="https://github.com/chemandante/leetcode/blob/master/02/63/m263.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 264 | ![M](img/M.png) [Ugly Number II](https://leetcode.com/problems/ugly-number-ii/) | | <a href="https://github.com/chemandante/leetcode/blob/master/02/64/m264.py" target="_blank"><img src="img/py.png"></a> |
-| 278 | ![E](img/E.png) [First Bad Version](https://leetcode.com/problems/first-bad-version/) | | <a href="https://github.com/chemandante/leetcode/blob/master/02/78/m278.py" target="_blank"><img src="img/py.png"></a> |
-| 304 | ![M](img/M.png) [Range Sum Query 2D - Immutable](https://leetcode.com/problems/range-sum-query-2d-immutable/) | | <a href="https://github.com/chemandante/leetcode/blob/master/03/04/m304.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 307 | ![M](img/M.png) [Range Sum Query - Mutable](https://leetcode.com/problems/range-sum-query-mutable/) | | <a href="https://github.com/chemandante/leetcode/blob/master/03/07/m307.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 315 | ![H](img/H.png) [Count of Smaller Numbers After Self](https://leetcode.com/problems/count-of-smaller-numbers-after-self/) | | <a href="https://github.com/chemandante/leetcode/blob/master/03/15/m315.swift" target="_blank"><img src="img/sw.png"></a> <a href="https://github.com/chemandante/leetcode/blob/master/03/15/m315.c" target="_blank"><img src="img/c.png"></a> |
-| 326 | ![E](img/E.png) [Power of Three](https://leetcode.com/problems/power-of-three/) | | <a href="https://github.com/chemandante/leetcode/blob/master/03/26/m326.py" target="_blank"><img src="img/py.png"></a> |
-| 342 | ![E](img/E.png) [Power of Four](https://leetcode.com/problems/power-of-four/) | | <a href="https://github.com/chemandante/leetcode/blob/master/03/42/m342.py" target="_blank"><img src="img/py.png"></a> |
-| 350 | ![E](img/E.png) [Intersection of Two Arrays II](https://leetcode.com/problems/intersection-of-two-arrays-ii/) | | <a href="https://github.com/chemandante/leetcode/blob/master/03/50/m350.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 367 | ![E](img/E.png) [Valid Perfect Square](https://leetcode.com/problems/valid-perfect-square/) | | <a href="https://github.com/chemandante/leetcode/blob/master/03/67/m367.py" target="_blank"><img src="img/py.png"></a> |
-| 374 | ![E](img/E.png) [Guess Number Higher or Lower](https://leetcode.com/problems/guess-number-higher-or-lower/) | | <a href="https://github.com/chemandante/leetcode/blob/master/03/74/m374.py" target="_blank"><img src="img/py.png"></a> |
-| 377 | ![M](img/M.png) [Combination Sum IV](https://leetcode.com/problems/combination-sum-iv/) | | <a href="https://github.com/chemandante/leetcode/blob/master/03/77/m377.py" target="_blank"><img src="img/py.png"></a> |
-| 378 | ![M](img/M.png) [Kth Smallest Element in a Sorted Matrix](https://leetcode.com/problems/kth-smallest-element-in-a-sorted-matrix/) | | <a href="https://github.com/chemandante/leetcode/blob/master/03/78/m378.py" target="_blank"><img src="img/py.png"></a> |
-| 383 | ![E](img/E.png) [Ransom Note](https://leetcode.com/problems/ransom-note/) | | <a href="https://github.com/chemandante/leetcode/blob/master/03/83/m383.swift" target="_blank"><img src="img/sw.png"></a> |
-| 387 | ![E](img/E.png) [First Unique Character in a String](https://leetcode.com/problems/first-unique-character-in-a-string/) | | <a href="https://github.com/chemandante/leetcode/blob/master/03/87/m387.py" target="_blank"><img src="img/py.png"></a> |
-| 429 | ![M](img/M.png) [N-ary Tree Level Order Traversal](https://leetcode.com/problems/n-ary-tree-level-order-traversal/) | | <a href="https://github.com/chemandante/leetcode/blob/master/04/29/m429.py" target="_blank"><img src="img/py.png"></a> |
-| 441 | ![E](img/E.png) [Arranging Coins](https://leetcode.com/problems/arranging-coins/) | | <a href="https://github.com/chemandante/leetcode/blob/master/04/41/m441.swift" target="_blank"><img src="img/sw.png"></a> |
-| 462 | ![M](img/M.png) [Minimum Moves to Equal Array Elements II](https://leetcode.com/problems/minimum-moves-to-equal-array-elements-ii/) | | <a href="https://github.com/chemandante/leetcode/blob/master/04/62/m462.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 633 | ![M](img/M.png) [Sum of Square Numbers](https://leetcode.com/problems/sum-of-square-numbers/) | | <a href="https://github.com/chemandante/leetcode/blob/master/06/33/m633.py" target="_blank"><img src="img/py.png"></a> |
-| 637 | ![E](img/E.png) [Average of Levels in Binary Tree](https://leetcode.com/problems/average-of-levels-in-binary-tree/) | | <a href="https://github.com/chemandante/leetcode/blob/master/06/37/m0637.c" target="_blank"><img src="img/c.png"></a> |
-| 668 | ![H](img/H.png) [Kth Smallest Number in Multiplication Table](https://leetcode.com/problems/kth-smallest-number-in-multiplication-table/) | | <a href="https://github.com/chemandante/leetcode/blob/master/06/68/m668.swift" target="_blank"><img src="img/sw.png"></a> |
-| 695 | ![M](img/M.png) [Max Area of Island](https://leetcode.com/problems/max-area-of-island/) | | <a href="https://github.com/chemandante/leetcode/blob/master/06/95/m695.swift" target="_blank"><img src="img/sw.png"></a> <a href="https://github.com/chemandante/leetcode/blob/master/06/95/m695.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 704 | ![E](img/E.png) [Binary Search](https://leetcode.com/problems/binary-search/) | | <a href="https://github.com/chemandante/leetcode/blob/master/07/04/m704.py" target="_blank"><img src="img/py.png"></a> <a href="https://github.com/chemandante/leetcode/blob/master/07/04/m704.swift" target="_blank"><img src="img/sw.png"></a> |
-| 729 | ![M](img/M.png) [My Calendar I](https://leetcode.com/problems/my-calendar-i/) | | <a href="https://github.com/chemandante/leetcode/blob/master/07/29/m729.py" target="_blank"><img src="img/py.png"></a> |
-| 733 | ![E](img/E.png) [Flood Fill](https://leetcode.com/problems/flood-fill/) | | <a href="https://github.com/chemandante/leetcode/blob/master/07/33/m733.py" target="_blank"><img src="img/py.png"></a> |
-| 744 | ![E](img/E.png) [Find Smallest Letter Greater Than Target](https://leetcode.com/problems/find-smallest-letter-greater-than-target/) | | <a href="https://github.com/chemandante/leetcode/blob/master/07/44/m744.py" target="_blank"><img src="img/py.png"></a> |
-| 786 | ![M](img/M.png) [K-th Smallest Prime Fraction](https://leetcode.com/problems/k-th-smallest-prime-fraction/) | | <a href="https://github.com/chemandante/leetcode/blob/master/07/86/m786.py" target="_blank"><img src="img/py.png"></a> |
-| 804 | ![E](img/E.png) [Unique Morse Code Words](https://leetcode.com/problems/unique-morse-code-words/) | | <a href="https://github.com/chemandante/leetcode/blob/master/08/04/m804.py" target="_blank"><img src="img/py.png"></a> |
-| 814 | ![M](img/M.png) [Binary Tree Pruning](https://leetcode.com/problems/binary-tree-pruning/) | | <a href="https://github.com/chemandante/leetcode/blob/master/08/14/m814.swift" target="_blank"><img src="img/sw.png"></a> |
-| 852 | ![M](img/M.png) [Peak Index in a Mountain Array](https://leetcode.com/problems/peak-index-in-a-mountain-array/) | | <a href="https://github.com/chemandante/leetcode/blob/master/08/52/m852.py" target="_blank"><img src="img/py.png"></a> |
-| 858 | ![M](img/M.png) [Mirror Reflection](https://leetcode.com/problems/mirror-reflection/) | | <a href="https://github.com/chemandante/leetcode/blob/master/08/58/m858.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 867 | ![E](img/E.png) [Transpose Matrix](https://leetcode.com/problems/transpose-matrix/) | | <a href="https://github.com/chemandante/leetcode/blob/master/08/67/m867.py" target="_blank"><img src="img/py.png"></a> |
-| 871 | ![H](img/H.png) [Minimum Number of Refueling Stops](https://leetcode.com/problems/minimum-number-of-refueling-stops/) | | <a href="https://github.com/chemandante/leetcode/blob/master/08/71/m871.py" target="_blank"><img src="img/py.png"></a> |
-| 890 | ![M](img/M.png) [Find and Replace Pattern](https://leetcode.com/problems/find-and-replace-pattern/) | | <a href="https://github.com/chemandante/leetcode/blob/master/08/90/m890.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 967 | ![M](img/M.png) [Numbers With Same Consecutive Differences](https://leetcode.com/problems/numbers-with-same-consecutive-differences/) | | <a href="https://github.com/chemandante/leetcode/blob/master/09/67/m967.swift" target="_blank"><img src="img/sw.png"></a> |
-| 987 | ![H](img/H.png) [Vertical Order Traversal of a Binary Tree](https://leetcode.com/problems/vertical-order-traversal-of-a-binary-tree/) | | <a href="https://github.com/chemandante/leetcode/blob/master/09/87/m987.py" target="_blank"><img src="img/py.png"></a> |
-| 1048 | ![M](img/M.png) [Longest String Chain](https://leetcode.com/problems/longest-string-chain/) | | <a href="https://github.com/chemandante/leetcode/blob/master/10/48/m1048.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 1175 | ![E](img/E.png) [Prime Arrangements](https://leetcode.com/problems/prime-arrangements/) | | <a href="https://github.com/chemandante/leetcode/blob/master/1175/m1175.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 1250 | ![H](img/H.png) [Check If It Is a Good Array](https://leetcode.com/problems/check-if-it-is-a-good-array/) | | <a href="https://github.com/chemandante/leetcode/blob/master/12/50/m1250.py" target="_blank"><img src="img/py.png"></a> |
-| 1254 | ![M](img/M.png) [Number of Closed Islands](https://leetcode.com/problems/number-of-closed-islands/) | | <a href="https://github.com/chemandante/leetcode/blob/master/12/54/m1254.py" target="_blank"><img src="img/py.png"></a> |
-| 1332 | ![E](img/E.png) [Remove Palindromic Subsequences](https://leetcode.com/problems/remove-palindromic-subsequences/) | | <a href="https://github.com/chemandante/leetcode/blob/master/13/32/m1332.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 1337 | ![E](img/E.png) [The K Weakest Rows in a Matrix](https://leetcode.com/problems/the-k-weakest-rows-in-a-matrix/) | | <a href="https://github.com/chemandante/leetcode/blob/master/13/37/m1337.py" target="_blank"><img src="img/py.png"></a> |
-| 1338 | ![M](img/M.png) [Reduce Array Size to The Half](https://leetcode.com/problems/reduce-array-size-to-the-half/) | | <a href="https://github.com/chemandante/leetcode/blob/master/13/38/m1338.py" target="_blank"><img src="img/py.png"></a> |
-| 1346 | ![E](img/E.png) [Check If N and Its Double Exist](https://leetcode.com/problems/check-if-n-and-its-double-exist/) | | <a href="https://github.com/chemandante/leetcode/blob/master/13/46/m1346.py" target="_blank"><img src="img/py.png"></a> |
-| 1351 | ![E](img/E.png) [Count Negative Numbers in a Sorted Matrix](https://leetcode.com/problems/count-negative-numbers-in-a-sorted-matrix/) | | <a href="https://github.com/chemandante/leetcode/blob/master/13/51/m1351.py" target="_blank"><img src="img/py.png"></a> |
-| 1385 | ![E](img/E.png) [Find the Distance Value Between Two Arrays](https://leetcode.com/problems/find-the-distance-value-between-two-arrays/) | | <a href="https://github.com/chemandante/leetcode/blob/master/13/85/m1385.py" target="_blank"><img src="img/py.png"></a> |
-| 1423 | ![M](img/M.png) [Maximum Points You Can Obtain from Cards](https://leetcode.com/problems/maximum-points-you-can-obtain-from-cards/) | | <a href="https://github.com/chemandante/leetcode/blob/master/14/23/m1423.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 1447 | ![M](img/M.png) [Simplified Fractions](https://leetcode.com/problems/simplified-fractions/) | | <a href="https://github.com/chemandante/leetcode/blob/master/14/47/m1447.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 1448 | ![M](img/M.png) [Count Good Nodes in Binary Tree](https://leetcode.com/problems/count-good-nodes-in-binary-tree/) | | <a href="https://github.com/chemandante/leetcode/blob/master/14/48/m1448.py" target="_blank"><img src="img/py.png"></a> |
-| 1480 | ![E](img/E.png) [Running Sum of 1d Array](https://leetcode.com/problems/running-sum-of-1d-array/) | | <a href="https://github.com/chemandante/leetcode/blob/master/14/80/m1480.c" target="_blank"><img src="img/c.png"></a> |
-| 1539 | ![E](img/E.png) [Kth Missing Positive Number](https://leetcode.com/problems/kth-missing-positive-number/) | | <a href="https://github.com/chemandante/leetcode/blob/master/15/39/m1539.swift" target="_blank"><img src="img/sw.png"></a> |
-| 1608 | ![E](img/E.png) [Special Array With X Elements Greater Than or Equal X](https://leetcode.com/problems/special-array-with-x-elements-greater-than-or-equal-x/) | | <a href="https://github.com/chemandante/leetcode/blob/master/16/08/m1608.swift" target="_blank"><img src="img/sw.png"></a> |
-| 1647 | ![M](img/M.png) [Minimum Deletions to Make Character Frequencies Unique](https://leetcode.com/problems/minimum-deletions-to-make-character-frequencies-unique/) | | <a href="https://github.com/chemandante/leetcode/blob/master/16/47/m1647.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 1689 | ![M](img/M.png) [Partitioning Into Minimum Number Of Deci-Binary Numbers](https://leetcode.com/problems/partitioning-into-minimum-number-of-deci-binary-numbers/) | | <a href="https://github.com/chemandante/leetcode/blob/master/16/89/m1689.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 1710 | ![E](img/E.png) [Maximum Units on a Truck](https://leetcode.com/problems/maximum-units-on-a-truck/) | | <a href="https://github.com/chemandante/leetcode/blob/master/17/10/m1710.cpp" target="_blank"><img src="img/cpp.png"></a> |
-| 1855 | ![M](img/M.png) [Maximum Distance Between a Pair of Values](https://leetcode.com/problems/maximum-distance-between-a-pair-of-values/) | | <a href="https://github.com/chemandante/leetcode/blob/master/18/55/m1855.py" target="_blank"><img src="img/py.png"></a> |
-| 2091 | ![M](img/M.png) [Removing Minimum and Maximum From Array](https://leetcode.com/problems/removing-minimum-and-maximum-from-array/) | | <a href="https://github.com/chemandante/leetcode/blob/master/20/91/m2091.py" target="_blank"><img src="img/py.png"></a> |
-| 2183 | ![H](img/H.png) [Count Array Pairs Divisible by K](https://leetcode.com/problems/count-array-pairs-divisible-by-k/) | | <a href="https://github.com/chemandante/leetcode/blob/master/2183/m2183.py" target="_blank"><img src="img/py.png"></a> |
-| 2197 | ![H](img/H.png) [Replace Non-Coprime Numbers in Array](https://leetcode.com/problems/replace-non-coprime-numbers-in-array/) | | <a href="https://github.com/chemandante/leetcode/blob/master/2197/m2197.py" target="_blank"><img src="img/py.png"></a> |
-| 2280 | ![M](img/M.png) [Minimum Lines to Represent a Line Chart](https://leetcode.com/problems/minimum-lines-to-represent-a-line-chart/) | | <a href="https://github.com/chemandante/leetcode/blob/master/22/80/m2280.cpp" target="_blank"><img src="img/cpp.png"></a> |
-
-### Basic algorithm implementations
-
-#### Binary indexed tree (Fenwick tree)
-
-| No. | Solutions where implemented | Lang | Notes |
-|:---:|-----------------------------|:----:|-------|
-| 315 | <a href="https://github.com/chemandante/leetcode/tree/master/03/15" target="_blank">Count of Smaller Numbers After Self</a> | ![](img/sw.png) ![](img/c.png) | Tree for counting numbers less than X |
-
-#### Binary search
-
-| No. | Solutions where implemented | Lang | Notes |
-|:---:|-----------------------------|:----:|-------|
-| 34 | <a href="https://github.com/chemandante/leetcode/tree/master/00/34" target="_blank">Find First and Last Position of Element in Sorted Array</a> | ![](img/py.png) ![](img/cpp.png) | Search for leftmost and rightmost in series of equals |
-| 35 | <a href="https://github.com/chemandante/leetcode/tree/master/00/35" target="_blank">Search Insert Position</a> | ![](img/py.png) | Search for leftmost |
-| 74 | <a href="https://github.com/chemandante/leetcode/tree/master/00/74" target="_blank">Search a 2D Matrix</a> | ![](img/py.png) ![](img/cpp.png) | Simple search with linear indexing of 2D matrix |
-| 240 | <a href="https://github.com/chemandante/leetcode/tree/master/02/40" target="_blank">Search a 2D Matrix II</a> | ![](img/cpp.png) | Simple search |
-| 704 | <a href="https://github.com/chemandante/leetcode/tree/master/07/04" target="_blank">Binary Search</a> | ![](img/py.png) ![](img/sw.png) | Simple search |
-
-#### Greatest common divisor (GCD)
-
-| No. | Solutions where implemented | Lang | Notes |
-|:---:|-----------------------------|:----:|-------|
-| 1447 | <a href="https://github.com/chemandante/leetcode/tree/master/14/47" target="_blank">Simplified Fractions</a> | ![](img/cpp.png) |  |
-| 2280 | <a href="https://github.com/chemandante/leetcode/tree/master/22/80" target="_blank">Minimum Lines to Represent a Line Chart</a> | ![](img/cpp.png) |  |
-
-#### Single-linked list
-
-| No. | Solutions where implemented | Lang | Notes |
-|:---:|-----------------------------|:----:|-------|
-| 25 | <a href="https://github.com/chemandante/leetcode/tree/master/00/25" target="_blank">Reverse Nodes in k-Group</a> | ![](img/py.png) |  |
-| 92 | <a href="https://github.com/chemandante/leetcode/tree/master/00/92" target="_blank">Reverse Linked List II</a> | ![](img/py.png) |  |
-
-
-### Other helpers
-
-| Helper | Solution | Lang |
-|--------|----------|:----:|
-| `Py` implementation of ListNode's `__str__` and `__repr__` | 25.&ensp;Reverse Nodes in k-Group | <a href="https://github.com/chemandante/leetcode/blob/master/00/25/m25.py" target="_blank"><img src="img/py.png"></a> |
-| Dynamic array | 637.&ensp;Average of Levels in Binary Tree | <a href="https://github.com/chemandante/leetcode/blob/master/06/37/m0637.c" target="_blank"><img src="img/c.png"></a> |
-| `Swift` queue using single-linked list | 695.&ensp;Max Area of Island | <a href="https://github.com/chemandante/leetcode/blob/master/06/95/m695.swift" target="_blank"><img src="img/sw.png"></a> |
-| Building TreeNode’s tree from array | 814.&ensp;Binary Tree Pruning | <a href="https://github.com/chemandante/leetcode/blob/master/08/14/m814.swift" target="_blank"><img src="img/sw.png"></a> |
-| Building TreeNode's tree from array | 987.&ensp;Vertical Order Traversal of a Binary Tree | <a href="https://github.com/chemandante/leetcode/blob/master/09/87/m987.py" target="_blank"><img src="img/py.png"></a> |
+Here is the list of solved problems. Language images are clickable and lead to the solution file.
+
+| No.  | Description (link to Leetcode)                                                                                                                                    | Explanation |               Lang               |
+|:----:|-------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------|:--------------------------------:|
+| 2 | ![M](img/M.png) [Add Two Numbers](https://leetcode.com/problems/add-two-numbers/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/02/m2.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 3 | ![M](img/M.png) [Longest Substring Without Repeating Characters](https://leetcode.com/problems/longest-substring-without-repeating-characters/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/03/m3.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 5 | ![M](img/M.png) [Longest Palindromic Substring](https://leetcode.com/problems/longest-palindromic-substring/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/05/m5.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 7 | ![M](img/M.png) [Reverse Integer](https://leetcode.com/problems/reverse-integer/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/07/m7.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 13 | ![E](img/E.png) [Roman to Integer](https://leetcode.com/problems/roman-to-integer/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/13/m13.py" target="_blank"><img src="img/py.png"></a> |
+| 25 | ![H](img/H.png) [Reverse Nodes in k-Group](https://leetcode.com/problems/reverse-nodes-in-k-group/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/25/m25.py" target="_blank"><img src="img/py.png"></a> |
+| 30 | ![H](img/H.png) [Substring with Concatenation of All Words](https://leetcode.com/problems/substring-with-concatenation-of-all-words/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/30/m30.py" target="_blank"><img src="img/py.png"></a> |
+| 33 | ![M](img/M.png) [Search in Rotated Sorted Array](https://leetcode.com/problems/search-in-rotated-sorted-array/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/33/m33.py" target="_blank"><img src="img/py.png"></a> |
+| 34 | ![M](img/M.png) [Find First and Last Position of Element in Sorted Array](https://leetcode.com/problems/find-first-and-last-position-of-element-in-sorted-array/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/34/m34.py" target="_blank"><img src="img/py.png"></a> <a href="https://github.com/chemandante/leetcode/blob/master/00/34/m34.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 35 | ![E](img/E.png) [Search Insert Position](https://leetcode.com/problems/search-insert-position/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/35/m35.py" target="_blank"><img src="img/py.png"></a> |
+| 41 | ![H](img/H.png) [First Missing Positive](https://leetcode.com/problems/first-missing-positive/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/41/m41.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 50 | ![M](img/M.png) [Pow(x, n)](https://leetcode.com/problems/powx-n/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/50/m50.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 60 | ![H](img/H.png) [Permutation Sequence](https://leetcode.com/problems/permutation-sequence/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/60/m60.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 62 | ![M](img/M.png) [Unique Paths](https://leetcode.com/problems/unique-paths/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/62/m62.py" target="_blank"><img src="img/py.png"></a> |
+| 67 | ![E](img/E.png) [Add Binary](https://leetcode.com/problems/add-binary/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/67/m67.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 69 | ![E](img/E.png) [Sqrt(x)](https://leetcode.com/problems/sqrtx/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/69/m69.py" target="_blank"><img src="img/py.png"></a> <a href="https://github.com/chemandante/leetcode/blob/master/00/69/m69.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 74 | ![M](img/M.png) [Search a 2D Matrix](https://leetcode.com/problems/search-a-2d-matrix/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/74/m74.py" target="_blank"><img src="img/py.png"></a> <a href="https://github.com/chemandante/leetcode/blob/master/00/74/m74.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 86 | ![M](img/M.png) [Partition List](https://leetcode.com/problems/partition-list/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/86/m86.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 88 | ![E](img/E.png) [Merge Sorted Array](https://leetcode.com/problems/merge-sorted-array/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/88/m88.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 89 | ![M](img/M.png) [Gray Code](https://leetcode.com/problems/gray-code/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/89/m89.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 92 | ![M](img/M.png) [Reverse Linked List II](https://leetcode.com/problems/reverse-linked-list-ii/) | | <a href="https://github.com/chemandante/leetcode/blob/master/00/92/m92.py" target="_blank"><img src="img/py.png"></a> |
+| 102 | ![M](img/M.png) [Binary Tree Level Order Traversal](https://leetcode.com/problems/binary-tree-level-order-traversal/) | | <a href="https://github.com/chemandante/leetcode/blob/master/01/02/m102.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 114 | ![M](img/M.png) [Flatten Binary Tree to Linked List](https://leetcode.com/problems/flatten-binary-tree-to-linked-list/) | | <a href="https://github.com/chemandante/leetcode/blob/master/01/14/m114.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 118 | ![E](img/E.png) [Pascal's Triangle](https://leetcode.com/problems/pascals-triangle/) | | <a href="https://github.com/chemandante/leetcode/blob/master/01/18/m118.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 119 | ![E](img/E.png) [Pascal's Triangle II](https://leetcode.com/problems/pascals-triangle-ii/) | | <a href="https://github.com/chemandante/leetcode/blob/master/01/19/m119.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 136 | ![E](img/E.png) [Single Number](https://leetcode.com/problems/single-number/) | | <a href="https://github.com/chemandante/leetcode/blob/master/01/36/m136_x64.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 137 | ![M](img/M.png) [Single Number II](https://leetcode.com/problems/single-number-ii/) | | <a href="https://github.com/chemandante/leetcode/blob/master/01/37/m137.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 153 | ![M](img/M.png) [Find Minimum in Rotated Sorted Array](https://leetcode.com/problems/find-minimum-in-rotated-sorted-array/) | | <a href="https://github.com/chemandante/leetcode/blob/master/01/53/m153.swift" target="_blank"><img src="img/sw.png"></a> |
+| 167 | ![M](img/M.png) [Two Sum II - Input Array Is Sorted](https://leetcode.com/problems/two-sum-ii-input-array-is-sorted/) | | <a href="https://github.com/chemandante/leetcode/blob/master/01/67/m167.swift" target="_blank"><img src="img/sw.png"></a> <a href="https://github.com/chemandante/leetcode/blob/master/01/67/m167.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 172 | ![M](img/M.png) [Factorial Trailing Zeroes](https://leetcode.com/problems/factorial-trailing-zeroes/) | | <a href="https://github.com/chemandante/leetcode/blob/master/01/72/m172.py" target="_blank"><img src="img/py.png"></a> <a href="https://github.com/chemandante/leetcode/blob/master/01/72/m172.swift" target="_blank"><img src="img/sw.png"></a> |
+| 200 | ![M](img/M.png) [Number of Islands](https://leetcode.com/problems/number-of-islands/) | | <a href="https://github.com/chemandante/leetcode/blob/master/02/00/m200.py" target="_blank"><img src="img/py.png"></a> |
+| 202 | ![E](img/E.png) [Happy Number](https://leetcode.com/problems/happy-number/) | | <a href="https://github.com/chemandante/leetcode/blob/master/02/02/m202.py" target="_blank"><img src="img/py.png"></a> |
+| 204 | ![M](img/M.png) [Count Primes](https://leetcode.com/problems/count-primes/) | | <a href="https://github.com/chemandante/leetcode/blob/master/02/04/m204.py" target="_blank"><img src="img/py.png"></a> <a href="https://github.com/chemandante/leetcode/blob/master/02/04/m204.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 206 | ![E](img/E.png) [Reverse Linked List](https://leetcode.com/problems/reverse-linked-list/) | | <a href="https://github.com/chemandante/leetcode/blob/master/02/06/m206.py" target="_blank"><img src="img/py.png"></a> |
+| 215 | ![M](img/M.png) [Kth Largest Element in an Array](https://leetcode.com/problems/kth-largest-element-in-an-array/) | | <a href="https://github.com/chemandante/leetcode/blob/master/02/15/m215.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 234 | ![E](img/E.png) [Palindrome Linked List](https://leetcode.com/problems/palindrome-linked-list/) | | <a href="https://github.com/chemandante/leetcode/blob/master/02/34/m234.py" target="_blank"><img src="img/py.png"></a> |
+| 235 | ![E](img/E.png) [Lowest Common Ancestor of a Binary Search Tree](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-search-tree/) | | <a href="https://github.com/chemandante/leetcode/blob/master/02/35/m235.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 236 | ![M](img/M.png) [Lowest Common Ancestor of a Binary Tree](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree/) | | <a href="https://github.com/chemandante/leetcode/blob/master/02/36/m236.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 240 | ![M](img/M.png) [Search a 2D Matrix II](https://leetcode.com/problems/search-a-2d-matrix-ii/) | | <a href="https://github.com/chemandante/leetcode/blob/master/02/40/m240.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 242 | ![E](img/E.png) [Valid Anagram](https://leetcode.com/problems/valid-anagram/) | | <a href="https://github.com/chemandante/leetcode/blob/master/02/42/m242.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 260 | ![M](img/M.png) [Single Number III](https://leetcode.com/problems/single-number-iii/) | | <a href="https://github.com/chemandante/leetcode/blob/master/02/60/m260.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 263 | ![E](img/E.png) [Ugly Number](https://leetcode.com/problems/ugly-number/) | | <a href="https://github.com/chemandante/leetcode/blob/master/02/63/m263.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 264 | ![M](img/M.png) [Ugly Number II](https://leetcode.com/problems/ugly-number-ii/) | | <a href="https://github.com/chemandante/leetcode/blob/master/02/64/m264.py" target="_blank"><img src="img/py.png"></a> |
+| 278 | ![E](img/E.png) [First Bad Version](https://leetcode.com/problems/first-bad-version/) | | <a href="https://github.com/chemandante/leetcode/blob/master/02/78/m278.py" target="_blank"><img src="img/py.png"></a> |
+| 304 | ![M](img/M.png) [Range Sum Query 2D - Immutable](https://leetcode.com/problems/range-sum-query-2d-immutable/) | | <a href="https://github.com/chemandante/leetcode/blob/master/03/04/m304.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 307 | ![M](img/M.png) [Range Sum Query - Mutable](https://leetcode.com/problems/range-sum-query-mutable/) | | <a href="https://github.com/chemandante/leetcode/blob/master/03/07/m307.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 315 | ![H](img/H.png) [Count of Smaller Numbers After Self](https://leetcode.com/problems/count-of-smaller-numbers-after-self/) | | <a href="https://github.com/chemandante/leetcode/blob/master/03/15/m315.swift" target="_blank"><img src="img/sw.png"></a> <a href="https://github.com/chemandante/leetcode/blob/master/03/15/m315.c" target="_blank"><img src="img/c.png"></a> |
+| 326 | ![E](img/E.png) [Power of Three](https://leetcode.com/problems/power-of-three/) | | <a href="https://github.com/chemandante/leetcode/blob/master/03/26/m326.py" target="_blank"><img src="img/py.png"></a> |
+| 342 | ![E](img/E.png) [Power of Four](https://leetcode.com/problems/power-of-four/) | | <a href="https://github.com/chemandante/leetcode/blob/master/03/42/m342.py" target="_blank"><img src="img/py.png"></a> |
+| 350 | ![E](img/E.png) [Intersection of Two Arrays II](https://leetcode.com/problems/intersection-of-two-arrays-ii/) | | <a href="https://github.com/chemandante/leetcode/blob/master/03/50/m350.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 367 | ![E](img/E.png) [Valid Perfect Square](https://leetcode.com/problems/valid-perfect-square/) | | <a href="https://github.com/chemandante/leetcode/blob/master/03/67/m367.py" target="_blank"><img src="img/py.png"></a> |
+| 374 | ![E](img/E.png) [Guess Number Higher or Lower](https://leetcode.com/problems/guess-number-higher-or-lower/) | | <a href="https://github.com/chemandante/leetcode/blob/master/03/74/m374.py" target="_blank"><img src="img/py.png"></a> |
+| 377 | ![M](img/M.png) [Combination Sum IV](https://leetcode.com/problems/combination-sum-iv/) | | <a href="https://github.com/chemandante/leetcode/blob/master/03/77/m377.py" target="_blank"><img src="img/py.png"></a> |
+| 378 | ![M](img/M.png) [Kth Smallest Element in a Sorted Matrix](https://leetcode.com/problems/kth-smallest-element-in-a-sorted-matrix/) | | <a href="https://github.com/chemandante/leetcode/blob/master/03/78/m378.py" target="_blank"><img src="img/py.png"></a> |
+| 383 | ![E](img/E.png) [Ransom Note](https://leetcode.com/problems/ransom-note/) | | <a href="https://github.com/chemandante/leetcode/blob/master/03/83/m383.swift" target="_blank"><img src="img/sw.png"></a> |
+| 387 | ![E](img/E.png) [First Unique Character in a String](https://leetcode.com/problems/first-unique-character-in-a-string/) | | <a href="https://github.com/chemandante/leetcode/blob/master/03/87/m387.py" target="_blank"><img src="img/py.png"></a> |
+| 429 | ![M](img/M.png) [N-ary Tree Level Order Traversal](https://leetcode.com/problems/n-ary-tree-level-order-traversal/) | | <a href="https://github.com/chemandante/leetcode/blob/master/04/29/m429.py" target="_blank"><img src="img/py.png"></a> |
+| 441 | ![E](img/E.png) [Arranging Coins](https://leetcode.com/problems/arranging-coins/) | | <a href="https://github.com/chemandante/leetcode/blob/master/04/41/m441.swift" target="_blank"><img src="img/sw.png"></a> |
+| 462 | ![M](img/M.png) [Minimum Moves to Equal Array Elements II](https://leetcode.com/problems/minimum-moves-to-equal-array-elements-ii/) | | <a href="https://github.com/chemandante/leetcode/blob/master/04/62/m462.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 633 | ![M](img/M.png) [Sum of Square Numbers](https://leetcode.com/problems/sum-of-square-numbers/) | | <a href="https://github.com/chemandante/leetcode/blob/master/06/33/m633.py" target="_blank"><img src="img/py.png"></a> |
+| 637 | ![E](img/E.png) [Average of Levels in Binary Tree](https://leetcode.com/problems/average-of-levels-in-binary-tree/) | | <a href="https://github.com/chemandante/leetcode/blob/master/06/37/m0637.c" target="_blank"><img src="img/c.png"></a> |
+| 668 | ![H](img/H.png) [Kth Smallest Number in Multiplication Table](https://leetcode.com/problems/kth-smallest-number-in-multiplication-table/) | | <a href="https://github.com/chemandante/leetcode/blob/master/06/68/m668.swift" target="_blank"><img src="img/sw.png"></a> |
+| 695 | ![M](img/M.png) [Max Area of Island](https://leetcode.com/problems/max-area-of-island/) | | <a href="https://github.com/chemandante/leetcode/blob/master/06/95/m695.swift" target="_blank"><img src="img/sw.png"></a> <a href="https://github.com/chemandante/leetcode/blob/master/06/95/m695.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 704 | ![E](img/E.png) [Binary Search](https://leetcode.com/problems/binary-search/) | | <a href="https://github.com/chemandante/leetcode/blob/master/07/04/m704.py" target="_blank"><img src="img/py.png"></a> <a href="https://github.com/chemandante/leetcode/blob/master/07/04/m704.swift" target="_blank"><img src="img/sw.png"></a> |
+| 729 | ![M](img/M.png) [My Calendar I](https://leetcode.com/problems/my-calendar-i/) | | <a href="https://github.com/chemandante/leetcode/blob/master/07/29/m729.py" target="_blank"><img src="img/py.png"></a> |
+| 733 | ![E](img/E.png) [Flood Fill](https://leetcode.com/problems/flood-fill/) | | <a href="https://github.com/chemandante/leetcode/blob/master/07/33/m733.py" target="_blank"><img src="img/py.png"></a> |
+| 744 | ![E](img/E.png) [Find Smallest Letter Greater Than Target](https://leetcode.com/problems/find-smallest-letter-greater-than-target/) | | <a href="https://github.com/chemandante/leetcode/blob/master/07/44/m744.py" target="_blank"><img src="img/py.png"></a> |
+| 786 | ![M](img/M.png) [K-th Smallest Prime Fraction](https://leetcode.com/problems/k-th-smallest-prime-fraction/) | | <a href="https://github.com/chemandante/leetcode/blob/master/07/86/m786.py" target="_blank"><img src="img/py.png"></a> |
+| 804 | ![E](img/E.png) [Unique Morse Code Words](https://leetcode.com/problems/unique-morse-code-words/) | | <a href="https://github.com/chemandante/leetcode/blob/master/08/04/m804.py" target="_blank"><img src="img/py.png"></a> |
+| 814 | ![M](img/M.png) [Binary Tree Pruning](https://leetcode.com/problems/binary-tree-pruning/) | | <a href="https://github.com/chemandante/leetcode/blob/master/08/14/m814.swift" target="_blank"><img src="img/sw.png"></a> |
+| 852 | ![M](img/M.png) [Peak Index in a Mountain Array](https://leetcode.com/problems/peak-index-in-a-mountain-array/) | | <a href="https://github.com/chemandante/leetcode/blob/master/08/52/m852.py" target="_blank"><img src="img/py.png"></a> |
+| 858 | ![M](img/M.png) [Mirror Reflection](https://leetcode.com/problems/mirror-reflection/) | | <a href="https://github.com/chemandante/leetcode/blob/master/08/58/m858.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 867 | ![E](img/E.png) [Transpose Matrix](https://leetcode.com/problems/transpose-matrix/) | | <a href="https://github.com/chemandante/leetcode/blob/master/08/67/m867.py" target="_blank"><img src="img/py.png"></a> |
+| 871 | ![H](img/H.png) [Minimum Number of Refueling Stops](https://leetcode.com/problems/minimum-number-of-refueling-stops/) | | <a href="https://github.com/chemandante/leetcode/blob/master/08/71/m871.py" target="_blank"><img src="img/py.png"></a> |
+| 890 | ![M](img/M.png) [Find and Replace Pattern](https://leetcode.com/problems/find-and-replace-pattern/) | | <a href="https://github.com/chemandante/leetcode/blob/master/08/90/m890.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 967 | ![M](img/M.png) [Numbers With Same Consecutive Differences](https://leetcode.com/problems/numbers-with-same-consecutive-differences/) | | <a href="https://github.com/chemandante/leetcode/blob/master/09/67/m967.swift" target="_blank"><img src="img/sw.png"></a> |
+| 987 | ![H](img/H.png) [Vertical Order Traversal of a Binary Tree](https://leetcode.com/problems/vertical-order-traversal-of-a-binary-tree/) | | <a href="https://github.com/chemandante/leetcode/blob/master/09/87/m987.py" target="_blank"><img src="img/py.png"></a> |
+| 1020 | ![M](img/M.png) [Number of Enclaves](https://leetcode.com/problems/number-of-enclaves/) | | <a href="https://github.com/chemandante/leetcode/blob/master/10/20/m1020.swift" target="_blank"><img src="img/sw.png"></a> |
+| 1048 | ![M](img/M.png) [Longest String Chain](https://leetcode.com/problems/longest-string-chain/) | | <a href="https://github.com/chemandante/leetcode/blob/master/10/48/m1048.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 1175 | ![E](img/E.png) [Prime Arrangements](https://leetcode.com/problems/prime-arrangements/) | | <a href="https://github.com/chemandante/leetcode/blob/master/1175/m1175.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 1250 | ![H](img/H.png) [Check If It Is a Good Array](https://leetcode.com/problems/check-if-it-is-a-good-array/) | | <a href="https://github.com/chemandante/leetcode/blob/master/12/50/m1250.py" target="_blank"><img src="img/py.png"></a> |
+| 1254 | ![M](img/M.png) [Number of Closed Islands](https://leetcode.com/problems/number-of-closed-islands/) | | <a href="https://github.com/chemandante/leetcode/blob/master/12/54/m1254.py" target="_blank"><img src="img/py.png"></a> |
+| 1332 | ![E](img/E.png) [Remove Palindromic Subsequences](https://leetcode.com/problems/remove-palindromic-subsequences/) | | <a href="https://github.com/chemandante/leetcode/blob/master/13/32/m1332.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 1337 | ![E](img/E.png) [The K Weakest Rows in a Matrix](https://leetcode.com/problems/the-k-weakest-rows-in-a-matrix/) | | <a href="https://github.com/chemandante/leetcode/blob/master/13/37/m1337.py" target="_blank"><img src="img/py.png"></a> |
+| 1338 | ![M](img/M.png) [Reduce Array Size to The Half](https://leetcode.com/problems/reduce-array-size-to-the-half/) | | <a href="https://github.com/chemandante/leetcode/blob/master/13/38/m1338.py" target="_blank"><img src="img/py.png"></a> |
+| 1346 | ![E](img/E.png) [Check If N and Its Double Exist](https://leetcode.com/problems/check-if-n-and-its-double-exist/) | | <a href="https://github.com/chemandante/leetcode/blob/master/13/46/m1346.py" target="_blank"><img src="img/py.png"></a> |
+| 1351 | ![E](img/E.png) [Count Negative Numbers in a Sorted Matrix](https://leetcode.com/problems/count-negative-numbers-in-a-sorted-matrix/) | | <a href="https://github.com/chemandante/leetcode/blob/master/13/51/m1351.py" target="_blank"><img src="img/py.png"></a> |
+| 1385 | ![E](img/E.png) [Find the Distance Value Between Two Arrays](https://leetcode.com/problems/find-the-distance-value-between-two-arrays/) | | <a href="https://github.com/chemandante/leetcode/blob/master/13/85/m1385.py" target="_blank"><img src="img/py.png"></a> |
+| 1423 | ![M](img/M.png) [Maximum Points You Can Obtain from Cards](https://leetcode.com/problems/maximum-points-you-can-obtain-from-cards/) | | <a href="https://github.com/chemandante/leetcode/blob/master/14/23/m1423.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 1447 | ![M](img/M.png) [Simplified Fractions](https://leetcode.com/problems/simplified-fractions/) | | <a href="https://github.com/chemandante/leetcode/blob/master/14/47/m1447.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 1448 | ![M](img/M.png) [Count Good Nodes in Binary Tree](https://leetcode.com/problems/count-good-nodes-in-binary-tree/) | | <a href="https://github.com/chemandante/leetcode/blob/master/14/48/m1448.py" target="_blank"><img src="img/py.png"></a> |
+| 1480 | ![E](img/E.png) [Running Sum of 1d Array](https://leetcode.com/problems/running-sum-of-1d-array/) | | <a href="https://github.com/chemandante/leetcode/blob/master/14/80/m1480.c" target="_blank"><img src="img/c.png"></a> |
+| 1539 | ![E](img/E.png) [Kth Missing Positive Number](https://leetcode.com/problems/kth-missing-positive-number/) | | <a href="https://github.com/chemandante/leetcode/blob/master/15/39/m1539.swift" target="_blank"><img src="img/sw.png"></a> |
+| 1608 | ![E](img/E.png) [Special Array With X Elements Greater Than or Equal X](https://leetcode.com/problems/special-array-with-x-elements-greater-than-or-equal-x/) | | <a href="https://github.com/chemandante/leetcode/blob/master/16/08/m1608.swift" target="_blank"><img src="img/sw.png"></a> |
+| 1647 | ![M](img/M.png) [Minimum Deletions to Make Character Frequencies Unique](https://leetcode.com/problems/minimum-deletions-to-make-character-frequencies-unique/) | | <a href="https://github.com/chemandante/leetcode/blob/master/16/47/m1647.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 1689 | ![M](img/M.png) [Partitioning Into Minimum Number Of Deci-Binary Numbers](https://leetcode.com/problems/partitioning-into-minimum-number-of-deci-binary-numbers/) | | <a href="https://github.com/chemandante/leetcode/blob/master/16/89/m1689.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 1710 | ![E](img/E.png) [Maximum Units on a Truck](https://leetcode.com/problems/maximum-units-on-a-truck/) | | <a href="https://github.com/chemandante/leetcode/blob/master/17/10/m1710.cpp" target="_blank"><img src="img/cpp.png"></a> |
+| 1855 | ![M](img/M.png) [Maximum Distance Between a Pair of Values](https://leetcode.com/problems/maximum-distance-between-a-pair-of-values/) | | <a href="https://github.com/chemandante/leetcode/blob/master/18/55/m1855.py" target="_blank"><img src="img/py.png"></a> |
+| 2091 | ![M](img/M.png) [Removing Minimum and Maximum From Array](https://leetcode.com/problems/removing-minimum-and-maximum-from-array/) | | <a href="https://github.com/chemandante/leetcode/blob/master/20/91/m2091.py" target="_blank"><img src="img/py.png"></a> |
+| 2183 | ![H](img/H.png) [Count Array Pairs Divisible by K](https://leetcode.com/problems/count-array-pairs-divisible-by-k/) | | <a href="https://github.com/chemandante/leetcode/blob/master/2183/m2183.py" target="_blank"><img src="img/py.png"></a> |
+| 2197 | ![H](img/H.png) [Replace Non-Coprime Numbers in Array](https://leetcode.com/problems/replace-non-coprime-numbers-in-array/) | | <a href="https://github.com/chemandante/leetcode/blob/master/2197/m2197.py" target="_blank"><img src="img/py.png"></a> |
+| 2280 | ![M](img/M.png) [Minimum Lines to Represent a Line Chart](https://leetcode.com/problems/minimum-lines-to-represent-a-line-chart/) | | <a href="https://github.com/chemandante/leetcode/blob/master/22/80/m2280.cpp" target="_blank"><img src="img/cpp.png"></a> |
+
+### Basic algorithm implementations
+
+#### Binary indexed tree (Fenwick tree)
+
+| No. | Solutions where implemented | Lang | Notes |
+|:---:|-----------------------------|:----:|-------|
+| 315 | <a href="https://github.com/chemandante/leetcode/tree/master/03/15" target="_blank">Count of Smaller Numbers After Self</a> | ![](img/sw.png) ![](img/c.png) | Tree for counting numbers less than X |
+
+#### Binary search
+
+| No. | Solutions where implemented | Lang | Notes |
+|:---:|-----------------------------|:----:|-------|
+| 34 | <a href="https://github.com/chemandante/leetcode/tree/master/00/34" target="_blank">Find First and Last Position of Element in Sorted Array</a> | ![](img/py.png) ![](img/cpp.png) | Search for leftmost and rightmost in series of equals |
+| 35 | <a href="https://github.com/chemandante/leetcode/tree/master/00/35" target="_blank">Search Insert Position</a> | ![](img/py.png) | Search for leftmost |
+| 74 | <a href="https://github.com/chemandante/leetcode/tree/master/00/74" target="_blank">Search a 2D Matrix</a> | ![](img/py.png) ![](img/cpp.png) | Simple search with linear indexing of 2D matrix |
+| 240 | <a href="https://github.com/chemandante/leetcode/tree/master/02/40" target="_blank">Search a 2D Matrix II</a> | ![](img/cpp.png) | Simple search |
+| 704 | <a href="https://github.com/chemandante/leetcode/tree/master/07/04" target="_blank">Binary Search</a> | ![](img/py.png) ![](img/sw.png) | Simple search |
+
+#### Greatest common divisor (GCD)
+
+| No. | Solutions where implemented | Lang | Notes |
+|:---:|-----------------------------|:----:|-------|
+| 1447 | <a href="https://github.com/chemandante/leetcode/tree/master/14/47" target="_blank">Simplified Fractions</a> | ![](img/cpp.png) |  |
+| 2280 | <a href="https://github.com/chemandante/leetcode/tree/master/22/80" target="_blank">Minimum Lines to Represent a Line Chart</a> | ![](img/cpp.png) |  |
+
+#### Single-linked list
+
+| No. | Solutions where implemented | Lang | Notes |
+|:---:|-----------------------------|:----:|-------|
+| 25 | <a href="https://github.com/chemandante/leetcode/tree/master/00/25" target="_blank">Reverse Nodes in k-Group</a> | ![](img/py.png) |  |
+| 92 | <a href="https://github.com/chemandante/leetcode/tree/master/00/92" target="_blank">Reverse Linked List II</a> | ![](img/py.png) |  |
+
+
+### Other helpers
+
+| Helper | Solution | Lang |
+|--------|----------|:----:|
+| `Py` implementation of ListNode's `__str__` and `__repr__` | 25.&ensp;Reverse Nodes in k-Group | <a href="https://github.com/chemandante/leetcode/blob/master/00/25/m25.py" target="_blank"><img src="img/py.png"></a> |
+| Dynamic array | 637.&ensp;Average of Levels in Binary Tree | <a href="https://github.com/chemandante/leetcode/blob/master/06/37/m0637.c" target="_blank"><img src="img/c.png"></a> |
+| `Swift` queue using single-linked list | 695.&ensp;Max Area of Island | <a href="https://github.com/chemandante/leetcode/blob/master/06/95/m695.swift" target="_blank"><img src="img/sw.png"></a> |
+| Building TreeNode’s tree from array | 814.&ensp;Binary Tree Pruning | <a href="https://github.com/chemandante/leetcode/blob/master/08/14/m814.swift" target="_blank"><img src="img/sw.png"></a> |
+| Building TreeNode's tree from array | 987.&ensp;Vertical Order Traversal of a Binary Tree | <a href="https://github.com/chemandante/leetcode/blob/master/09/87/m987.py" target="_blank"><img src="img/py.png"></a> |