Mock CCO '19 Contest 2 Problem 3 - A Cactus Problem

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Points: 15 (partial)

Time limit: 0.6s

Memory limit: 162M

Problem type

Given a cactus graph, compute the maximum distance between two vertices.

Constraints

$1 \le N \le 5 \cdot 10^4$ ~1 \le N \le 5 \cdot 10^4~

$0 \le M \le 10^4$ ~0 \le M \le 10^4~

$2 \le K_i \le 10^3$ ~2 \le K_i \le 10^3~

Input Specification

The first line contains two space-separated integers, $N$ ~N~ and $M$ ~M~. There are $N$ ~N~ vertices labeled from $1$ ~1~ to $N$ ~N~.

$M$ ~M~ lines follow. Each line starts with an integer $K_i$ ~K_i~, followed by $K_i$ ~K_i~ space-separated integers. Adjacent integers in each line are connected with an edge. The graph is guaranteed to be a connected cactus.

Output Specification

Output the diameter of the graph.

Sample Input

15 3
9 1 2 3 4 5 6 7 8 3
7 2 9 10 11 12 13 10
5 2 14 9 15 10

Sample Output

Comments

-6

avis commented on Oct. 20, 2020, 8:58 a.m.

http://poj.org/problem?id=3567

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