LeetCode OJ：Maximum Depth of Binary Tree（二叉树最大深度）

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.

求二叉树深度，直接看代码：

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    int maxDepth(TreeNode* root) {
        if(root == NULL) return 0;
        _max = 1;
        tranverse(root->left, 1);
        tranverse(root->right, 1);
        return _max;
    }
    void tranverse(TreeNode * node, int count)
    {
        if(node == NULL)
            return;
        else{ 
            if(count + 1 > _max)
                _max = count + 1;
            tranverse(node->left, count + 1);
            tranverse(node->right, count + 1);
        }
    }
public:
    int _max;
};

 java版的如下所示，上面的递归写的还是太麻烦了，下面的简单很多哈：

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public int maxDepth(TreeNode root) {
        if(root == null)
            return 0;
        return tranverse(root, 0);
    }
    
    public int tranverse(TreeNode root, int val){
        if(root.left == null && root.right == null)
            return val+1;
        int leftDep = 0, rightDep = 0;
        if(root.left != null)
            leftDep = tranverse(root.left, val + 1);
        if(root.right != null)
            rightDep = tranverse(root.right, val + 1);
       return Math.max(leftDep, rightDep);
    }
}