LeetCode Topics

Array

0001-two-sum
0004-median-of-two-sorted-arrays
0011-container-with-most-water
0015-3sum
0016-3sum-closest
0018-4sum
0026-remove-duplicates-from-sorted-array
0027-remove-element
0031-next-permutation
0034-find-first-and-last-position-of-element-in-sorted-array
0035-search-insert-position
0036-valid-sudoku
0041-first-missing-positive
0042-trapping-rain-water
0045-jump-game-ii
0048-rotate-image
0053-maximum-subarray
0054-spiral-matrix
0055-jump-game
0056-merge-intervals
0057-insert-interval
0066-plus-one
0073-set-matrix-zeroes
0074-search-a-2d-matrix
0075-sort-colors
0080-remove-duplicates-from-sorted-array-ii
0081-search-in-rotated-sorted-array-ii
0088-merge-sorted-array
0118-pascals-triangle
0121-best-time-to-buy-and-sell-stock
0122-best-time-to-buy-and-sell-stock-ii
0123-best-time-to-buy-and-sell-stock-iii
0128-longest-consecutive-sequence
0134-gas-station
0136-single-number
0152-maximum-product-subarray
0153-find-minimum-in-rotated-sorted-array
0162-find-peak-element
0167-two-sum-ii-input-array-is-sorted
0189-rotate-array
0209-minimum-size-subarray-sum
0215-kth-largest-element-in-an-array
0217-contains-duplicate
0219-contains-duplicate-ii
0228-summary-ranges
0229-majority-element-ii
0238-product-of-array-except-self
0268-missing-number
0274-h-index
0283-move-zeroes
0287-find-the-duplicate-number
0289-game-of-life
0347-top-k-frequent-elements
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii
0380-insert-delete-getrandom-o1
0416-partition-equal-subset-sum
0452-minimum-number-of-arrows-to-burst-balloons
0455-assign-cookies
0457-circular-array-loop
0485-max-consecutive-ones
0500-keyboard-row
0540-single-element-in-a-sorted-array
0560-subarray-sum-equals-k
0605-can-place-flowers
0643-maximum-average-subarray-i
0724-find-pivot-index
0745-find-smallest-letter-greater-than-target
0890-lemonade-change
0907-koko-eating-bananas
0952-word-subsets
0966-binary-subarrays-with-sum
1034-subarrays-with-k-different-integers
1046-max-consecutive-ones-iii
1364-tuple-with-same-product
1370-count-number-of-nice-subarrays
1408-find-the-smallest-divisor-given-a-threshold
1524-string-matching-in-an-array
1538-maximum-points-you-can-obtain-from-cards
1586-longest-subarray-of-1s-after-deleting-one-element
1798-max-number-of-k-sum-pairs
1878-check-if-array-is-sorted-and-rotated
1895-minimum-number-of-operations-to-move-all-balls-to-each-box
1927-maximum-ascending-subarray-sum
1966-frequency-of-the-most-frequent-element
2271-rearrange-array-elements-by-sign
2292-counting-words-with-a-given-prefix
2350-find-closest-number-to-zero
2358-number-of-ways-to-split-array
2448-count-number-of-bad-pairs
2465-shifting-letters-ii
2478-longest-nice-subarray
2486-most-frequent-even-element
2533-bitwise-xor-of-all-pairings
2685-first-completely-painted-row-or-column
2691-count-vowel-strings-in-ranges
2766-find-the-prefix-common-array-of-two-arrays
2792-neighboring-bitwise-xor
3236-smallest-missing-integer-greater-than-sequential-prefix-sum
3309-count-prefix-and-suffix-pairs-i
3372-longest-strictly-increasing-or-strictly-decreasing-subarray
3429-special-array-i
3434-find-the-number-of-distinct-colors-among-the-balls

Binary Search

0004-median-of-two-sorted-arrays
0034-find-first-and-last-position-of-element-in-sorted-array
0035-search-insert-position
0074-search-a-2d-matrix
0081-search-in-rotated-sorted-array-ii
0153-find-minimum-in-rotated-sorted-array
0162-find-peak-element
0167-two-sum-ii-input-array-is-sorted
0209-minimum-size-subarray-sum
0268-missing-number
0287-find-the-duplicate-number
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii
0374-guess-number-higher-or-lower
0540-single-element-in-a-sorted-array
0745-find-smallest-letter-greater-than-target
0907-koko-eating-bananas
1046-max-consecutive-ones-iii
1408-find-the-smallest-divisor-given-a-threshold
1966-frequency-of-the-most-frequent-element

Hash Table

0001-two-sum
0003-longest-substring-without-repeating-characters
0012-integer-to-roman
0036-valid-sudoku
0041-first-missing-positive
0073-set-matrix-zeroes
0076-minimum-window-substring
0128-longest-consecutive-sequence
0138-copy-list-with-random-pointer
0141-linked-list-cycle
0142-linked-list-cycle-ii
0160-intersection-of-two-linked-lists
0202-happy-number
0205-isomorphic-strings
0217-contains-duplicate
0219-contains-duplicate-ii
0229-majority-element-ii
0242-valid-anagram
0268-missing-number
0290-word-pattern
0347-top-k-frequent-elements
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii
0380-insert-delete-getrandom-o1
0383-ransom-note
0387-first-unique-character-in-a-string
0389-find-the-difference
0424-longest-repeating-character-replacement
0451-sort-characters-by-frequency
0457-circular-array-loop
0500-keyboard-row
0560-subarray-sum-equals-k
0952-word-subsets
0966-binary-subarrays-with-sum
1029-vertical-order-traversal-of-a-binary-tree
1034-subarrays-with-k-different-integers
1364-tuple-with-same-product
1370-count-number-of-nice-subarrays
1460-number-of-substrings-containing-all-three-characters
1502-construct-k-palindrome-strings
1798-max-number-of-k-sum-pairs
1890-sum-of-beauty-of-all-substrings
1915-check-if-one-string-swap-can-make-strings-equal
2059-unique-length-3-palindromic-subsequences
2427-first-letter-to-appear-twice
2448-count-number-of-bad-pairs
2486-most-frequent-even-element
2685-first-completely-painted-row-or-column
2766-find-the-prefix-common-array-of-two-arrays
3236-smallest-missing-integer-greater-than-sequential-prefix-sum
3434-find-the-number-of-distinct-colors-among-the-balls
3455-minimum-length-of-string-after-operations

Math

0007-reverse-integer
0009-palindrome-number
0012-integer-to-roman
0029-divide-two-integers
0048-rotate-image
0066-plus-one
0067-add-binary
0189-rotate-array
0202-happy-number
0231-power-of-two
0268-missing-number
0380-insert-delete-getrandom-o1
0412-fizz-buzz
0445-add-two-numbers-ii
1370-count-number-of-nice-subarrays
2032-largest-odd-number-in-string
2448-count-number-of-bad-pairs

Bit Manipulation

0029-divide-two-integers
0067-add-binary
0136-single-number
0231-power-of-two
0268-missing-number
0287-find-the-duplicate-number
0389-find-the-difference
2059-unique-length-3-palindromic-subsequences
2427-first-letter-to-appear-twice
2478-longest-nice-subarray
2509-minimize-xor
2533-bitwise-xor-of-all-pairings
2766-find-the-prefix-common-array-of-two-arrays
2792-neighboring-bitwise-xor

Sorting

0015-3sum
0016-3sum-closest
0018-4sum
0056-merge-intervals
0075-sort-colors
0088-merge-sorted-array
0148-sort-list
0215-kth-largest-element-in-an-array
0217-contains-duplicate
0229-majority-element-ii
0242-valid-anagram
0268-missing-number
0274-h-index
0347-top-k-frequent-elements
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii
0389-find-the-difference
0451-sort-characters-by-frequency
0452-minimum-number-of-arrows-to-burst-balloons
0455-assign-cookies
1029-vertical-order-traversal-of-a-binary-tree
1798-max-number-of-k-sum-pairs
1966-frequency-of-the-most-frequent-element
2646-kth-largest-sum-in-a-binary-tree
3236-smallest-missing-integer-greater-than-sequential-prefix-sum

Two Pointers

0005-longest-palindromic-substring
0011-container-with-most-water
0015-3sum
0016-3sum-closest
0018-4sum
0019-remove-nth-node-from-end-of-list
0026-remove-duplicates-from-sorted-array
0027-remove-element
0028-find-the-index-of-the-first-occurrence-in-a-string
0031-next-permutation
0042-trapping-rain-water
0075-sort-colors
0080-remove-duplicates-from-sorted-array-ii
0088-merge-sorted-array
0125-valid-palindrome
0141-linked-list-cycle
0142-linked-list-cycle-ii
0148-sort-list
0151-reverse-words-in-a-string
0160-intersection-of-two-linked-lists
0167-two-sum-ii-input-array-is-sorted
0189-rotate-array
0202-happy-number
0234-palindrome-linked-list
0283-move-zeroes
0287-find-the-duplicate-number
0344-reverse-string
0345-reverse-vowels-of-a-string
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii
0392-is-subsequence
0443-string-compression
0455-assign-cookies
0457-circular-array-loop
0647-palindromic-substrings
0908-middle-of-the-linked-list
1798-max-number-of-k-sum-pairs
1850-minimum-length-of-string-after-deleting-similar-ends
1894-merge-strings-alternately
2216-delete-the-middle-node-of-a-linked-list
2271-rearrange-array-elements-by-sign

String

0003-longest-substring-without-repeating-characters
0005-longest-palindromic-substring
0008-string-to-integer-atoi
0012-integer-to-roman
0014-longest-common-prefix
0020-valid-parentheses
0022-generate-parentheses
0028-find-the-index-of-the-first-occurrence-in-a-string
0058-length-of-last-word
0067-add-binary
0076-minimum-window-substring
0125-valid-palindrome
0151-reverse-words-in-a-string
0205-isomorphic-strings
0242-valid-anagram
0290-word-pattern
0344-reverse-string
0345-reverse-vowels-of-a-string
0383-ransom-note
0387-first-unique-character-in-a-string
0389-find-the-difference
0392-is-subsequence
0412-fizz-buzz
0424-longest-repeating-character-replacement
0443-string-compression
0451-sort-characters-by-frequency
0459-repeated-substring-pattern
0500-keyboard-row
0647-palindromic-substrings
0812-rotate-string
0952-word-subsets
1078-remove-outermost-parentheses
1460-number-of-substrings-containing-all-three-characters
1502-construct-k-palindrome-strings
1524-string-matching-in-an-array
1537-maximum-score-after-splitting-a-string
1567-maximum-number-of-vowels-in-a-substring-of-given-length
1737-maximum-nesting-depth-of-the-parentheses
1850-minimum-length-of-string-after-deleting-similar-ends
1890-sum-of-beauty-of-all-substrings
1894-merge-strings-alternately
1895-minimum-number-of-operations-to-move-all-balls-to-each-box
1915-check-if-one-string-swap-can-make-strings-equal
2032-largest-odd-number-in-string
2059-unique-length-3-palindromic-subsequences
2221-check-if-a-parentheses-string-can-be-valid
2292-counting-words-with-a-given-prefix
2427-first-letter-to-appear-twice
2465-shifting-letters-ii
2691-count-vowel-strings-in-ranges
3309-count-prefix-and-suffix-pairs-i
3447-clear-digits
3455-minimum-length-of-string-after-operations

String Matching

0028-find-the-index-of-the-first-occurrence-in-a-string
0459-repeated-substring-pattern
0812-rotate-string
1524-string-matching-in-an-array
2292-counting-words-with-a-given-prefix
3309-count-prefix-and-suffix-pairs-i

Interactive

0374-guess-number-higher-or-lower

Dynamic Programming

0005-longest-palindromic-substring
0022-generate-parentheses
0042-trapping-rain-water
0045-jump-game-ii
0053-maximum-subarray
0055-jump-game
0118-pascals-triangle
0121-best-time-to-buy-and-sell-stock
0122-best-time-to-buy-and-sell-stock-ii
0123-best-time-to-buy-and-sell-stock-iii
0124-binary-tree-maximum-path-sum
0152-maximum-product-subarray
0392-is-subsequence
0416-partition-equal-subset-sum
0647-palindromic-substrings
1586-longest-subarray-of-1s-after-deleting-one-element

Matrix

0036-valid-sudoku
0048-rotate-image
0054-spiral-matrix
0073-set-matrix-zeroes
0074-search-a-2d-matrix
0289-game-of-life
2685-first-completely-painted-row-or-column

Prefix Sum

0209-minimum-size-subarray-sum
0238-product-of-array-except-self
0560-subarray-sum-equals-k
0724-find-pivot-index
0966-binary-subarrays-with-sum
1046-max-consecutive-ones-iii
1370-count-number-of-nice-subarrays
1537-maximum-score-after-splitting-a-string
1538-maximum-points-you-can-obtain-from-cards
1895-minimum-number-of-operations-to-move-all-balls-to-each-box
1966-frequency-of-the-most-frequent-element
2059-unique-length-3-palindromic-subsequences
2358-number-of-ways-to-split-array
2465-shifting-letters-ii
2691-count-vowel-strings-in-ranges

Divide and Conquer

0004-median-of-two-sorted-arrays
0053-maximum-subarray
0148-sort-list
0215-kth-largest-element-in-an-array
0347-top-k-frequent-elements

Sliding Window

0003-longest-substring-without-repeating-characters
0076-minimum-window-substring
0209-minimum-size-subarray-sum
0219-contains-duplicate-ii
0424-longest-repeating-character-replacement
0643-maximum-average-subarray-i
0966-binary-subarrays-with-sum
1034-subarrays-with-k-different-integers
1046-max-consecutive-ones-iii
1370-count-number-of-nice-subarrays
1460-number-of-substrings-containing-all-three-characters
1538-maximum-points-you-can-obtain-from-cards
1567-maximum-number-of-vowels-in-a-substring-of-given-length
1586-longest-subarray-of-1s-after-deleting-one-element
1966-frequency-of-the-most-frequent-element
2478-longest-nice-subarray

Tree

0094-binary-tree-inorder-traversal
0100-same-tree
0102-binary-tree-level-order-traversal
0103-binary-tree-zigzag-level-order-traversal
0104-maximum-depth-of-binary-tree
0110-balanced-binary-tree
0124-binary-tree-maximum-path-sum
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0515-find-largest-value-in-each-tree-row
0543-diameter-of-binary-tree
1029-vertical-order-traversal-of-a-binary-tree
2646-kth-largest-sum-in-a-binary-tree

Breadth-First Search

0100-same-tree
0102-binary-tree-level-order-traversal
0103-binary-tree-zigzag-level-order-traversal
0104-maximum-depth-of-binary-tree
0515-find-largest-value-in-each-tree-row
1029-vertical-order-traversal-of-a-binary-tree
2646-kth-largest-sum-in-a-binary-tree

Binary Tree

0094-binary-tree-inorder-traversal
0100-same-tree
0102-binary-tree-level-order-traversal
0103-binary-tree-zigzag-level-order-traversal
0104-maximum-depth-of-binary-tree
0110-balanced-binary-tree
0124-binary-tree-maximum-path-sum
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0515-find-largest-value-in-each-tree-row
0543-diameter-of-binary-tree
1029-vertical-order-traversal-of-a-binary-tree
2646-kth-largest-sum-in-a-binary-tree

Simulation

0054-spiral-matrix
0067-add-binary
0289-game-of-life
0412-fizz-buzz
2271-rearrange-array-elements-by-sign
3434-find-the-number-of-distinct-colors-among-the-balls
3447-clear-digits

Union Find

0128-longest-consecutive-sequence

Stack

0020-valid-parentheses
0042-trapping-rain-water
0094-binary-tree-inorder-traversal
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0155-min-stack
0225-implement-stack-using-queues
0232-implement-queue-using-stacks
0234-palindrome-linked-list
0445-add-two-numbers-ii
1078-remove-outermost-parentheses
1737-maximum-nesting-depth-of-the-parentheses
2221-check-if-a-parentheses-string-can-be-valid
3447-clear-digits

Linked List

0019-remove-nth-node-from-end-of-list
0083-remove-duplicates-from-sorted-list
0092-reverse-linked-list-ii
0138-copy-list-with-random-pointer
0141-linked-list-cycle
0142-linked-list-cycle-ii
0148-sort-list
0160-intersection-of-two-linked-lists
0206-reverse-linked-list
0234-palindrome-linked-list
0237-delete-node-in-a-linked-list
0328-odd-even-linked-list
0445-add-two-numbers-ii
0908-middle-of-the-linked-list
2216-delete-the-middle-node-of-a-linked-list

Greedy

0011-container-with-most-water
0045-jump-game-ii
0055-jump-game
0122-best-time-to-buy-and-sell-stock-ii
0134-gas-station
0452-minimum-number-of-arrows-to-burst-balloons
0455-assign-cookies
0605-can-place-flowers
0890-lemonade-change
1502-construct-k-palindrome-strings
1966-frequency-of-the-most-frequent-element
2032-largest-odd-number-in-string
2221-check-if-a-parentheses-string-can-be-valid
2509-minimize-xor

Trie

0014-longest-common-prefix
3309-count-prefix-and-suffix-pairs-i

Heap (Priority Queue)

0215-kth-largest-element-in-an-array
0347-top-k-frequent-elements
0451-sort-characters-by-frequency

Bucket Sort

0347-top-k-frequent-elements
0451-sort-characters-by-frequency

Counting

0229-majority-element-ii
0347-top-k-frequent-elements
0383-ransom-note
0387-first-unique-character-in-a-string
0451-sort-characters-by-frequency
1034-subarrays-with-k-different-integers
1364-tuple-with-same-product
1502-construct-k-palindrome-strings
1890-sum-of-beauty-of-all-substrings
1915-check-if-one-string-swap-can-make-strings-equal
2427-first-letter-to-appear-twice
2448-count-number-of-bad-pairs
2486-most-frequent-even-element
3455-minimum-length-of-string-after-operations

Quickselect

0215-kth-largest-element-in-an-array
0347-top-k-frequent-elements

Queue

0225-implement-stack-using-queues
0232-implement-queue-using-stacks
0387-first-unique-character-in-a-string

Recursion

0206-reverse-linked-list
0231-power-of-two
0234-palindrome-linked-list

Merge Sort

0148-sort-list

Design

0155-min-stack
0225-implement-stack-using-queues
0232-implement-queue-using-stacks
0380-insert-delete-getrandom-o1

Counting Sort

0274-h-index

Depth-First Search

0094-binary-tree-inorder-traversal
0100-same-tree
0104-maximum-depth-of-binary-tree
0110-balanced-binary-tree
0124-binary-tree-maximum-path-sum
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0515-find-largest-value-in-each-tree-row
0543-diameter-of-binary-tree
1029-vertical-order-traversal-of-a-binary-tree

Rolling Hash

3309-count-prefix-and-suffix-pairs-i

Hash Function

3309-count-prefix-and-suffix-pairs-i

Brainteaser

2533-bitwise-xor-of-all-pairings

Monotonic Stack

0042-trapping-rain-water

Backtracking

0022-generate-parentheses

Randomized

0380-insert-delete-getrandom-o1