HDU 5305 Friends (dfs)

HDU 5305 Friends (dfs)

 

Friends Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/65536 K (Java/Others)
Total Submission (s): 297 Accepted Submission (s): 127


Problem Description There are N People and M Pairs of friends. for every pair of friends, they can choose to become online friends (communicating using online applications) or offline friends (mostly using face-to-face communication ). however, everyone in these N People wants to have the same number of online and offline friends (I. e. If one person has X Onine friends, he or she must have X Offline friends too, but different people can have different number of online or offline friends). Please determine how many ways there are to satisfy their requirements.

Input The first line of the input is a single integer T (T = 100) , Indicating the number of testcases.

For each testcase, the first line contains two integers N (1 ≤ n ≤ 8) And M (0 ≤ m ≤ n (n −1) 2) , Indicating the number of people and the number of pairs of friends, respectively. Each of the next M Lines contains two numbers X And Y , Which mean X And Y Are friends. It is guaranteed that X = y And every friend relationship will appear at most once.

Output For each testcase, print one number indicating the answer.
Sample Input

23 31 22 33 14 41 22 33 44 1

Sample Output

02

Source

 

 

 

 

 

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