2015 多校联赛 ——HDU5344（水）

Problem Description

MZL loves xor very much.Now he gets an array A.The length of A is n.He wants to know the xor of all (Ai+Aj)(1≤i,j≤n)
The xor of an array B is defined as B1 xor B2...xor Bn

Input

Multiple test cases, the first line contains an integer T(no more than 20), indicating the number of cases.
Each test case contains four integers:n,m,z,l
A1=0,Ai=(Ai−1∗m+z) mod l
1≤m,z,l≤5∗105,n=5∗105

Output

For every test.print the answer.

Sample Input

2
3 5 5 7
6 8 8 9

Sample Output

14
16

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<vector>
#include<cmath>
typedef long long ll;
const int maxn = 0x3f3f3f3f;
using namespace std;
ll a[500010];

int main()
{
    int T;
    scanf("%d",&T);
    while(T--)
    {
        int n,m,k,l;
        memset(a,0,sizeof(a));
        scanf("%d%d%d%d",&n,&m,&k,&l);
        a[1] = 0;
        for(int i = 2;i <= n;i++)
           a[i] = (a[i-1]*m+k)%l;
        for(int i = 2;i <= n;i++)
           a[i]^=a[i-1];
        printf("%I64d\n",a[n]*2);
    }
    return 0;
}