LeetCode--Minimum Depth of Binary Tree

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.

解题思路：
1，注意左右子树的递归
2，递归出口，left， right同时为空，分别为空

class Solution {
public:
    int run(TreeNode *root) {
        if(root == NULL)
            return 0; 
        if(root->left == NULL)
            return run(root->right) + 1;
        if(root->right == NULL)
            return run(root->left) + 1;

        int lmin = run(root->left); 
        int rmin = run(root->right); 

        return min(lmin, rmin)+1;
    }
};