leetcode：Minimum Depth of Binary Tree 【Java】

一、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.
二、问题分析

利用迭代思想。

三、算法代码

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public int minDepth(TreeNode root) {
        return minDepth(root, false);
    }
    public int minDepth(TreeNode root, boolean hasbrother) {
        if (root == null) return hasbrother ? Integer.MAX_VALUE : 0;
        
        return 1 + Math.min(minDepth(root.left, root.right != null),
        minDepth(root.right, root.left != null));
}
}