【LeetCode】Maximum Depth of Binary Tree (二叉树最大深度)

题目描述：

Given a binary tree, find its maximum depth.

The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

思路：采用递归的思想，父结点的深度 = max{左右儿子深度} +1

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    int maxDepth(TreeNode *root) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        return func(root);
    }
    int func(TreeNode *root)
    {
        if(root == NULL) return 0;
        int leftdepth = func(root->left);
        int rightdepth =func(root->right);
        leftdepth = leftdepth>rightdepth? leftdepth+1:rightdepth+1;
        return leftdepth;
    }
};