HDU 5464 Clarke and problem

Problem Description

Clarke is a patient with multiple personality disorder. One day, Clarke turned into a student and read a book.
Suddenly, a difficult problem appears: 
You are given a sequence of number a1,a2,...,an and a number p. Count the number of the way to choose some of number(choose none of them is also a solution) from the sequence that sum of the numbers is a multiple of p(0 is also count as a multiple of p). Since the answer is very large, you only need to output the answer modulo 109+7

 

Input

The first line contains one integer T(1≤T≤10) - the number of test cases. 
T test cases follow. 
The first line contains two positive integers n,p(1≤n,p≤1000) 
The second line contains n integers a1,a2,...an(|ai|≤109).

 

Output

For each testcase print a integer, the answer.

 

Sample Input

12 31 2

 

Sample Output

2Hint:2 choice: choose none and choose all.
简单递推
#include<cstdio>#include<cstring>#include<cmath>#include<iostream>using namespace std;typedef long long LL;const int maxn = 1005;const LL base = 1e9 + 7;int T, n, m, x;LL f[maxn][maxn];int main(){    scanf("%d", &T);    while (T--)    {        scanf("%d%d", &n, &m);        memset(f, 0, sizeof(f));        f[0][0] = 1;        for (int i = 1; i <= n; i++)        {            scanf("%d", &x);            x = (x%m + m) % m;            for (int j = 0; j < m; j++)            {                f[i][(j + x) % m] = (f[i - 1][j] + f[i - 1][(j + x) % m]) % base;            }        }        printf("%I64d\n", f[n][0]);    }    return 0;}