题意 : 给出 N 个点,以及 M 条双向路,每一条路的权值代表你在这条路上到达终点需要那么时间,接下来给出 W 个虫洞,虫洞给出的形式为 A B C 代表能将你从 A 送到 B 点,并且回到 C 个时间点之前,也就是时光倒流了 C 个时间并且此时你在 B 点,现在问你是否能够在图上的这些点中走,使得在某一个点刚好碰到之前的自己 分析 : 冷静分析一下,只要是有负权回路的某一条边属于虫洞的,那么肯定是能在这个环上一直绕,直到遇到之前的自己,如果将虫洞看作一条负权边的话,那么问题就变成了只要存在负…
Wormholes Time Limit: 2000MS Memory Limit: 65536K Total Submissions: 36425 Accepted: 13320 Description While exploring his many farms, Farmer John has discovered a number of amazing wormholes. A wormhole is very peculiar because it is a one-way p…
Wormholes Time Limit: 2000MS Memory Limit: 65536K Total Submissions: 46123 Accepted: 17033 Description While exploring his many farms, Farmer John has discovered a number of amazing wormholes. A wormhole is very peculiar because it is a one-way path…
链接: http://poj.org/problem?id=3259 http://acm.hust.edu.cn/vjudge/contest/view.action?cid=22010#problem/B Wormholes Time Limit: 2000MS Memory Limit: 65536K Total Submissions: 25079 Accepted: 8946 Description While exploring his many farms, Farmer…
Wormholes Time Limit: 2000MS Memory Limit: 65536K Total Submissions: 37906 Accepted: 13954 Description While exploring his many farms, Farmer John has discovered a number of amazing wormholes. A wormhole is very peculiar because it is a one-way p…
题意:John的农场里n块地,m条路连接两块地,k个虫洞,虫洞是一条单向路,不但会把你传送到目的地,而且时间会倒退Ts.我们的任务是知道会不会在从某块地出发后又回来,看到了离开之前的自己. 思路:虫洞连接的边是负权值的,如果途中存在一个负环的话,他可以沿着这个换一直走,时间肯定为负值. #include<string.h> #include<stdio.h> const int N=510; const int inf=0x3fffffff; int start,num,n,dis…
Description While exploring his many farms, Farmer John has discovered a number of amazing wormholes. A wormhole is very peculiar because it is a one-way path that delivers you to its destination at a time that is BEFORE you entered the wormhole! Eac…