Writing Code-Codeforces511C**

http://codeforces.com/problemset/problem/544/C

完全背包

dp[i][j]表示第i行有j个bug

#include<stdio.h>
#include<string.h>

#define N 550

int dp[N][N], a[N];

int main()
{
    int n, m, b, MOD;

    while(scanf("%d%d%d%d", &n, &m, &b, &MOD)!=EOF)
    {
        int i, j, k, w, sum=;

        memset(dp, , sizeof(dp));
        memset(a, , sizeof(a));

        for(i=; i<n; i++)
            scanf("%d", &a[i]);

        for(i=; i<=m; i++)
        {
            w = i*a[i];
            if(w<=b) dp[i][w] = ;
        }

        for(i=; i<n; i++)
        for(j=; j<m; j++)
        for(k=; k<=b; k++)
        {
            if(dp[j][k])
            {
                int x = j-, y = k + a[i];
                if(y<=b)
                {
                    dp[x][y] += dp[j][k];
                    dp[x][y] %= MOD;
                }
            }
        }

        for(i=; i<=b; i++)
        {
            sum += dp[m][i];
            sum %= MOD;
        }

        printf("%d\n", sum);
    }
    return ;
}