3196. Wormholes

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 fields conveniently numbered .., paths, and 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 of his farms. No paths will take longer than seconds to travel and no wormhole can bring FJ back in time by more than seconds.

输入格式

  • Line : A single integer, . farm descriptions follow.
  • Line of each farm: Three space-separated integers respectively:
  • Lines .. of each farm: Three space-separated numbers that describe, respectively: a bidirectional path between and that requires seconds to traverse. Two fields might be connected by more than one path.
  • Lines .. of each farm: Three space-separated numbers that describe, respectively: A one way path from to that also moves the traveler back seconds.

输出格式

Lines ..: For each farm, output YES if FJ can achieve his goal, otherwise output NO.

样例

Input
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
Output
NO
YES

9 人解决,10 人已尝试。

18 份提交通过,共有 54 份提交。

5.6 EMB 奖励。

创建: 2 年,8 月前.

修改: 2 年,3 月前.

最后提交: 3 周,3 天前.

来源: USACO 2006 December Gold

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