LeetCode Minimum Depth of Binary Tree

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.

简单的考研题，求个最小深度嘛

/**
* 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;

return min(minDepth(root->right),minDepth(root->left))+1;
}
};