poj 3046 Ant Counting (DP多重背包变形)

#include <cstdio>
#include <cstring>
#include <iostream>
int T,A,S,B;
int hash[1010];
int dp[1010][10100];

const int MOD=1e6;
using namespace std;
int main(){

while(cin>>T>>A>>S>>B){
memset(hash,0,sizeof(hash));
for(int i = 1; i <= A; i++){
int u;
cin>>u;
hash[u]++;
}
memset(dp,0,sizeof(dp));
for(int i = 0; i <= hash[1]; i++) dp[1][i] = 1;//第一种取1~k
for(int i = 2; i <= T; i++)
for(int j = 0; j <= B; j ++){
for(int k = 0; k <= hash[i]; k++)
if(j >= k) {
dp[i][j] += dp[i-1][j-k];
dp[i][j] %= MOD;
}else break;
}
int sum = 0;
for(int i = S; i <= B; i++){
sum+= dp[T][i];
sum %= MOD;
}
cout<<sum<<endl;
}
return 0;
}