# LeetCode 104 Maximum Depth of Binary Tree DFS

2022-05-16 02:01:57  阅读：41  来源： 互联网

Given the root of a binary tree, return its maximum depth.

A binary tree's maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

### Solution

$\max(\ \text{dfs}(root.left, depth+1),\text{dfs}(root.right,depth+1)\ )$

/**
* 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 maxDepth(TreeNode* root) {
if(!root)return 0;
return dfs(root, 1);
}
int dfs(TreeNode* root, int depth){
if(!root->left && !root->right)return depth;
else if(root->left && !root->right)return dfs(root->left,depth+1);
else if(root->right && !root->left)return dfs(root->right,depth+1);
else return max(dfs(root->left,depth+1),dfs(root->right,depth+1));
}
};