12 人解决，13 人已尝试。
21 份提交通过，共有 73 份提交。
5.0 EMB 奖励。
单点时限: 2.0 sec
内存限制: 256 MB
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! Each of FJ’s farms comprises $N$ $(1 \leq N \leq 500)$ fields conveniently numbered $1$..$N$, $M$ $(1 \leq M \leq 2500)$ paths, and $W$ $(1 \leq W \leq 200)$ wormholes.
As FJ is an avid time-traveling fan, he wants to do the following: start at some field, travel through some paths and wormholes, and return to the starting field a time before his initial departure. Perhaps he will be able to meet himself :) .
To help FJ find out whether this is possible or not, he will supply you with complete maps to $F$ $(1 \leq F \leq 5)$ of his farms. No paths will take longer than $10~000$ seconds to travel and no wormhole can bring FJ back in time by more than $10~000$ seconds.
Lines $1$..$F$: For each farm, output YES if FJ can achieve his goal, otherwise output NO.
2 3 3 1 1 2 2 1 3 4 2 3 1 3 1 3 3 2 1 1 2 3 2 3 4 3 1 8
NO YES
12 人解决，13 人已尝试。
21 份提交通过，共有 73 份提交。
5.0 EMB 奖励。