求二叉树最小深度

问题描述：

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.

//提供一棵二叉树，找到它的最小深度（最小深度指的是树的根节点沿着最短路径到达最近的叶子节点，该叶子节点所在的深度//

//根结点的层数是1

//深度是指所有结点中最深的结点所在的层数

 

问题解决(c\c++)：

class Solution {

public:

    int run(TreeNode *root) {

        if(NULL == root)return 0;

        if(NULL == root->left && NULL == root->right)return 1;

        if(NULL == root->left)return run(root->right) + 1;

        else if(NULL == root->right)return run(root->left) + 1;

        else return min(run(root->left),run(root->right)) + 1;

    }

};