Perface
Problem A. Bad Horse
Problem
As the leader of the Evil League of Evil, Bad Horse has a lot of problems to deal with.
Most recently, there have been far too many arguments and far too much backstabbing in
the League, so much so that Bad Horse has decided to split the league into two
departments in order to separate troublesome members. Being the Thoroughbred of Sin,
Bad Horse isn't about to spend his valuable time figuring out how to split the League
members by himself. That what he's got you -- his loyal henchman -- for.
Input
The first line of the input gives the number of test cases, T. T test cases follow. Each test
case starts with a positive integer M on a line by itself -- the number of troublesome pairs
of League members. The next M lines each contain a pair of names, separated by a
single space.
Output
For each test case, output one line containing "Case #x: y", where x is the case number
(starting from 1) and y is either "Yes" or "No", depending on whether the League members
mentioned in the input can be split into two groups with neither of the groups containing a
troublesome pair.
Limits
1 ≤ T ≤ 100.
Each member name will consist of only letters and the underscore character.
Names are case-sensitive.
No pair will appear more than once in the same test case.
Each pair will contain two distinct League members.
Small dataset
1 ≤ M ≤ 10.
Large dataset
1 ≤ M ≤ 100.
Input Output
2 Case #1: Yes
1 Case #2: No
Dead_Bowie Fake_Thomas_Jefferson
3
Dead_Bowie Fake_Thomas_Jefferson
Fake_Thomas_Jefferson Fury_Leika
Fury_Leika Dead_Bowie
这题大概的意思就是:有个Bad Horse 要给他联盟里面的人分成两组,因为有些人在一起会闹矛盾,所以不能将他们分在一组里。现在的问题就是给出一系列这样的矛盾对,判断是否存在一种分组方法将他们分开,保证没有一组里会有两个人闹矛盾。(第一眼看到这题的时候读了很久们读懂,估计是没接触过这种题吧)