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.
Note: A leaf is a node with no children.
Example:
Given binary tree [3,9,20,null,null,15,7],
return its minimum depth = 2.
求最小的深度，二叉树，这道题目我认为数据是有问题的，所以有176个踩，
c++
class Solution {
public:
int minDepth(TreeNode* root) {
if(root==NULL) return ;
int lmin =;
int rmin =;
if(root->left!=NULL)
lmin = minDepth(root->left);
if(root->right!=NULL)
rmin = minDepth(root->right);
if(lmin==)
return rmin+;
if(rmin==)
return lmin+;
return min(lmin,rmin)+;
}
};