LeetCode 111. Minimum Depth of Binary Tree

题目链接：https://leetcode.com/PRoblems/minimum-depth-of-binary-tree/?tab=Description

题目描述:

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.

思路：这道题和 LeetCode 104. Maximum Depth of Binary Tree相反， 可以用同样的思路，但是要注意的是，当前节点左子树或者右子树为空时需要判断一下

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 minDepth(TreeNode* root) {        if(root==NULL)            return 0 ;        int depth1=minDepth(root->left);        int depth2=minDepth(root->right);        if(depth1==0&&depth2==0)            return 1;        else if(depth1==0&&depth2!=0)            return depth2+1;        else if(depth1!=0&&depth2==0)            return depth1+1;        else            return depth1<depth2?depth1+1:depth2+1;            }};