Couple doubi

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 1087    Accepted Submission(s): 762

Problem Description

DouBiXp has a girlfriend named DouBiNan.One day they felt very boring
and decided to play some games. The rule of this game is as following.
There are k balls on the desk. Every ball has a value and the value of
ith (i=1,2,...,k) ball is 1^i+2^i+...+(p-1)^i (mod p). Number p is a
prime number that is chosen by DouBiXp and his girlfriend. And then they
take balls in turn and DouBiNan first. After all the balls are token,
they compare the sum of values with the other ,and the person who get
larger sum will win the game. You should print “YES” if DouBiNan will
win the game. Otherwise you should print “NO”.

Input

Multiply Test Cases.
In the first line there are two Integers k and p(1<k,p<2^31).

Output

For each line, output an integer, as described above.

Sample Input

2 3
20 3

Sample Output

YES
NO

Author

FZU

Source

2014 Multi-University Training Contest 1

数论： 费马引理

官方解题报告：

代码：

#include<stdio.h>
 void main(){
 int k,p;
 while(~scanf("%d%d",&k,&p))
   k/=(p-1),puts(k&1)?"YES":"NO");
}