当前你的浏览器版本过低，网站已在兼容模式下运行，兼容模式仅提供最小功能支持，网站样式可能显示不正常。
请尽快升级浏览器以体验网站在线编辑、在线运行等功能。

建议使用的浏览器：

谷歌Chrome 火狐Firefox Opera浏览器 微软Edge浏览器 QQ浏览器 360浏览器 傲游浏览器

3256：Cow Picnic

题目描述

The cows are having a picnic! Each of Farmer John's K (1 ≤ K ≤ 100) cows is grazing in one of N (1 ≤ N ≤ 1,000) pastures, conveniently numbered 1...N. The pastures are connected by M (1 ≤ M ≤ 10,000) one-way paths (no path connects a pasture to itself).

The cows want to gather in the same pasture for their picnic, but (because of the one-way paths) some cows may only be able to get to some pastures. Help the cows out by figuring out how many pastures are reachable by all cows, and hence are possible picnic locations.

输入解释
Line 1: Three space-separated integers, respectively: K, N, and M
Lines 2..K+1: Line i+1 contains a single integer (1..N) which is the number of the pasture in which cow i is grazing.
Lines K+2..M+K+1: Each line contains two space-separated integers, respectively A and B (both 1..N and A != B), representing a one-way path from pasture A to pasture B.
输出解释
Line 1: The single integer that is the number of pastures that are reachable by all cows via the one-way paths.
输入样例 
2 4 4
2
3
1 2
1 4
2 3
3 4
输出样例 
2
提示
The cows can meet in pastures 3 or 4.
该题目是Virtual Judge题目，来自 北京大学POJ
题目来源 USACO 2006 December Silver
源链接： POJ-3256
最后修改于 2020-10-29T06:57:04+00:00 由爬虫自动更新
共提交 0 次
通过率 --%
时间上限 内存上限
2000 65536