687. Longest Univalue Path

最新推荐文章于 2024-04-04 16:00:00 发布

SHURamos

最新推荐文章于 2024-04-04 16:00:00 发布

阅读量1.2k

点赞数 1

分类专栏： Leetcode

本文链接：https://blog.youkuaiyun.com/SHURamos/article/details/78192558

版权

Leetcode 专栏收录该内容

220 篇文章

订阅专栏

本文介绍了一个二叉树问题，即寻找树中最长路径，该路径上的所有节点具有相同的值。此路径可能经过也可能不经过根节点。文章通过示例详细说明了如何计算路径长度，并给出了一个解决方案。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

Given a binary tree, find the length of the longest path where each node in the path has the same value. This path may or may not pass through the root.

Note: The length of path between two nodes is represented by the number of edges between them.

Example 1:

Input:

Output:

Example 2:

Input:

Output:

Note: The given binary tree has not more than 10000 nodes. The height of the tree is not more than 1000.

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    int re = 0;
    public int longestUnivaluePath(TreeNode root) {
		help(root, 0);
		return re;
	}

	public int help(TreeNode root, int n) {
		if (root == null)
			return 0;
		int left = help(root.left, root.val);
		int right = help(root.right, root.val);
		re = Math.max(re, left + right);
		return root.val == n ? Math.max(left, right) + 1 : 0;
	}
}