[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.

二叉树的遍历。递归遍历左右子树，返回最短的路径长度。递归结束的条件是，如果根为空，则返回0.

 /** * Definition for binary tree * public class TreeNode { *     int val; *     TreeNode left; *     TreeNode right; *     TreeNode(int x) { val = x; } * } */public 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;        return Math.min(run(root.left),run(root.right))+1;    }}