leetcode

Author: sgrade

leetcode/smallest-subtree-with-all-the-deepest-nodes.cpp

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+// 865. Smallest Subtree with all the Deepest Nodes
+// https://leetcode.com/problems/smallest-subtree-with-all-the-deepest-nodes/
+
+#include <utility>  // for std::pair
+
+// Definition for a binary tree node.
+struct TreeNode {
+  int val;
+  TreeNode* left;
+  TreeNode* right;
+  TreeNode() : val(0), left(nullptr), right(nullptr) {}
+  TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
+  TreeNode(int x, TreeNode* left, TreeNode* right)
+      : val(x), left(left), right(right) {}
+};
+
+// Based on Editorial's Approach 2: Recursion
+class Solution {
+ public:
+  TreeNode* subtreeWithAllDeepest(TreeNode* root) {
+    return GetDeepest(root).second;
+  }
+
+ private:
+  std::pair<int, TreeNode*> GetDeepest(TreeNode* node) {
+    if (node == nullptr) {
+      return {0, nullptr};
+    }
+    const auto& [left_dist, left_node] = GetDeepest(node->left);
+    const auto& [right_dist, right_node] = GetDeepest(node->right);
+    if (left_dist > right_dist) {
+      return {left_dist + 1, left_node};
+    }
+    if (right_dist > left_dist) {
+      return {right_dist + 1, right_node};
+    }
+    return {left_dist + 1, node};
+  }
+};