LeetCode *** 111. Minimum Depth of Binary Tree

题目：

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.



分析：

求二叉树的最小深度，其中注意细节：题目要求的是求根节点与最近的叶子节点的距离，如果根节点没有左子树或是右子树那么就需要注意最终的输出结果。分情况讨论即可。

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;
if(root->left==NULL)return minDepth(root->right)+1;
if(root->right==NULL)return minDepth(root->left)+1;
int right=minDepth(root->right)+1;
int left=minDepth(root->left)+1;
return left>right?right:left;
}

};