111. Minimum Depth of Binary Tree（DFS）

1. Description

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.

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2. Code

题目比较简单，与寻找最大depth类似。逐层寻找叶节点，第一次找到的那个就是最小深度的叶节点。记录一下代码而已。

/** * 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 minDepth(TreeNode* root) {        if(root == NULL) return 0;        if(root->left == NULL && root->right == NULL) return 1;        TreeNode * node = NULL;        int level = 0;        queue<TreeNode*> tmp;        tmp.push(root);        while( !tmp.empty()) {            level ++;            for(int i = 0, size = tmp.size(); i < size; i++) {                node = tmp.front();                tmp.pop();                if(node->left == NULL && node->right == NULL)                    return level;                if(node->left != NULL) {                    tmp.push(node->left);                }                if(node->right != NULL) {                    tmp.push(node->right);                }                       }           }        return level;       }};