PT07Z - Longest path in a tree

题目描述

You are given an unweighted, undirected tree. Write a program to output the length of the longest path (from one node to another) in that tree. The length of a path in this case is number of edges we traverse from source to destination.

输入格式

The first line of the input file contains one integer $N$ --- number of nodes in the tree ($0< N \le 10^4$). Next $N-1$ lines contain $N-1$ edges of that tree --- Each line contains a pair $(u,v)$ means there is an edge between node $u$ and node $v$.

输出格式

Print the length of the longest path on one line.

输入样例 #1

3
1 2
2 3

输出样例 #1

2

输入样例 #2

3
1 2
2 3

输出样例 #2

2

输入样例 #3

3
1 2
2 3

输出样例 #3

2

数据范围

The first line of the input file contains one integer $N$ --- number of nodes in the tree ($0< N \le 10^4$). Next $N-1$ lines contain $N-1$ edges of that tree --- Each line contains a pair $(u,v)$ means there is an edge between node $u$ and node $v$.