[leetcode]26 Minimum Depth of Binary Tree

题目链接：https://leetcode.com/problems/minimum-depth-of-binary-tree/
Runtimes：16ms

1、问题

Given a binary tree, find its minimum depth.
The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.

2、分析

层次遍历找最短路径

3、小结

有一些相关的题目，如Maximum Depth of Binary Tree

4、实现

/** * 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 minDepth(TreeNode *root) {        if(root == NULL)            return 0;        queue <int> iq;        queue <TreeNode*> tq;        iq.push(1);        tq.push(root);        while(iq.size() > 0 && tq.size() > 0)        {            int depth = iq.front(); iq.pop();            TreeNode *p = tq.front(); tq.pop();            if(p->left == NULL && p->right == NULL)                return depth;            if(p->left != NULL)            {                iq.push(depth + 1);                tq.push(p->left);            }            if(p->right != NULL)            {                iq.push(depth + 1);                tq.push(p->right);            }        }    }};