HDU 5666 Segment

Segment

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)
Total Submission(s): 1082    Accepted Submission(s): 398

Problem Description

    Silen August does not like to talk with others.She like to find some interesting problems.

    Today she finds an interesting problem.She finds a segment x+y=q.The segment intersect the axis and produce a delta.She links some line between (0,0) and the node on the segment whose coordinate are integers.

    Please calculate how many nodes are in the delta and not on the segments,output answer mod P.

 

Input

    First line has a number,T,means testcase number.

    Then,each line has two integers q,P.

    q is a prime number,and 2≤q≤1018,1≤P≤1018,1≤T≤10.

 

Output

    Output 1 number to each testcase,answer mod P.

 

Sample Input

1 2 107

 

Sample Output

0

 

题目就是求直线与坐标轴围成的区域内有多少个点（整数）我们可以发现 点的数量是成等差数列的  求和就ok了  注意数据范围 

import java.util.*;
import java.math.*;
public class Main {
    public static void main(String []args){
        Scanner cin=new Scanner(System.in);
        int n;
        BigInteger a,b,e;
        n=cin.nextInt();
        for(int i=1;i<=n;i++){
            a=cin.nextBigInteger();
            b=cin.nextBigInteger();
            BigInteger c=new BigInteger("2");
            BigInteger d=new BigInteger("1");
            a=a.subtract(c);
            e=a.multiply(a).add(a);
            e=e.divide(c);
            e=e.mod(b);
            System.out.println(e);
        }
    }

}