[leetcode]Maximum Depth of Binary Tree

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.

基本不用解释吧。

/**
 * 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 curMax;
    int maxDepth(TreeNode *root) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        curMax = -1;
        DepthFirst(root,0);
        return curMax+1;        
    }
    void DepthFirst(TreeNode * root,int depth)
    {
        if(root == NULL)
            return;
        if(root->left == NULL && root->right == NULL)
        {
            if(curMax < depth)
                curMax = depth;
            return;
        }
        DepthFirst(root->left,depth + 1);
        DepthFirst(root->right,depth + 1);
    }
};