Dec 24

2024-12-December-LeetCoding-Challenge/Find Minimum Diameter After Merging Two Trees.py

@@ -0,0 +1,65 @@
+from collections import deque
+from math import ceil
+from typing import List, Tuple
+
+
+class Solution:
+    def __build_adj_list(self, n: int, edges: List[int]) -> List[List[int]]:
+        adj_list = [[] for _ in range(n)]
+        for u, v in edges:
+            adj_list[u].append(v)
+            adj_list[v].append(u)
+        return adj_list
+
+    def __find_diameter(self, n: int, adj_list: List[List[int]]) -> int:
+        farthest_node, _ = self.__find_farthest_node(n, adj_list)
+        _, diameter = self.__find_farthest_node(n, adj_list, farthest_node)
+        return diameter
+
+    def __find_farthest_node(
+            self, n: int, adj_list: List[List[int]], source_node: int = 0
+    ) -> Tuple[int, int]:
+        queue = deque([source_node])
+        visited = [i == source_node for i in range(n)]
+
+        max_distance = 0
+        farthest_node = source_node
+
+        while queue:
+            for _ in range(len(queue)):
+                current_node = queue.popleft()
+                farthest_node = current_node
+                for neighbor in adj_list[current_node]:
+                    if not visited[neighbor]:
+                        visited[neighbor] = True
+                        queue.append(neighbor)
+            if queue:
+                max_distance += 1
+
+        return farthest_node, max_distance
+
+    def minimumDiameterAfterMerge(self, edges1: List[List[int]], edges2: List[List[int]]) -> int:
+        n, m = len(edges1) + 1, len(edges2) + 1
+
+        adj_list1 = self.__build_adj_list(n, edges1)
+        adj_list2 = self.__build_adj_list(m, edges2)
+
+        diameter1 = self.__find_diameter(n, adj_list1)
+        diameter2 = self.__find_diameter(m, adj_list2)
+
+        combined_diameter = ceil(diameter1 / 2) + ceil(diameter2 / 2) + 1
+        return max(diameter1, diameter2, combined_diameter)
+
+
+def main():
+    edges1 = [[0, 1], [0, 2], [0, 3]]
+    edges2 = [[0, 1]]
+    assert Solution().minimumDiameterAfterMerge(edges1, edges2) == 3
+
+    edges1 = [[0, 1], [0, 2], [0, 3], [2, 4], [2, 5], [3, 6], [2, 7]]
+    edges2 = [[0, 1], [0, 2], [0, 3], [2, 4], [2, 5], [3, 6], [2, 7]]
+    assert Solution().minimumDiameterAfterMerge(edges1, edges2) == 5
+
+
+if __name__ == '__main__':
+    main()

2024-12-December-LeetCoding-Challenge/README.md

@@ -26,7 +26,7 @@
 | December 21 | [2872. Maximum Number of K-Divisible Components](https://leetcode.com/problems/maximum-number-of-k-divisible-components/) | Hard | Unsolved |
 | December 22 | [2940. Find Building Where Alice and Bob Can Meet](https://leetcode.com/problems/find-building-where-alice-and-bob-can-meet/) | Hard | Unsolved |
 | December 23 | [2471. Minimum Number of Operations to Sort a Binary Tree by Level](https://leetcode.com/problems/minimum-number-of-operations-to-sort-a-binary-tree-by-level/) | Medium | Solved |
-| December 24 | []() |  |  |
+| December 24 | [3203. Find Minimum Diameter After Merging Two Trees](https://leetcode.com/problems/find-minimum-diameter-after-merging-two-trees/) | Hard | Unsolved |
 | December 25 | []() |  |  |
 | December 26 | []() |  |  |
 | December 27 | []() |  |  |
@@ -40,4 +40,4 @@
 | ---    | --- | --- | --- |
 | Easy   | 5 | 5 | 0 |
 | Medium | 16 | 10 | 6 |
-| Hard   | 2 | 0 | 2 |
+| Hard   | 3 | 0 | 3 |