2026/03/21

[LeetCode] 104 Maximum Depth of Binary Tree

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/**
 * 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) {}
 * };
 */
class Solution {
public:
  int dfs(TreeNode* node, int depth) {
    if (node == nullptr)
      return depth - 1;
    return max(dfs(node->left, depth + 1), dfs(node->right, depth + 1));
  }

  int maxDepth(TreeNode* root) {
    return dfs(root, 1);
  }
};