104. Maximum Depth of Binary Tree

题目

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.

题意

找出树的最大深度

分析

使用BFS.

实现

/** * 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) return 0;        queue<TreeNode*> q;        q.push(root);        int res = 0;        TreeNode *cur = root;        while (!q.empty()) {            int n = q.size();            while (n--) {                cur = q.front();                if (cur->left) q.push(cur->left);                if (cur->right) q.push(cur->right);                q.pop();            }            res++;        }        return res;    }};