1193

1193 - Dice (II)

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Time Limit: 3 second(s)

Memory Limit: 32 MB

You have N dices; each of them has K faces numbered from 1 to K. Now you can arrange the N dices in a line. If the summation of the top faces of the dices is S, you calculate the score as the multiplication of all the top faces.

Now you are given N, K, S; you have to calculate the summation of all the scores.

Input

Input starts with an integer T (≤ 25), denoting the number of test cases.

Each case contains three integers: N (1 ≤ N ≤ 1000) K (1 ≤ K ≤ 1000) S (0 ≤ S ≤ 15000).

Output

For each case print the case number and the result modulo 100000007.

Sample Input	Output for Sample Input
5 1 6 3 2 9 8 500 6 1000 800 800 10000 2 100 10	Case 1: 3 Case 2: 84 Case 3: 74335590 Case 4: 33274428 Case 5: 165

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PROBLEM SETTER: JANE ALAM JAN

思路:和1145差不多。

dp[i][j]表示前i次点数之和为j的数所有对数的各个的乘积之和。

那么dp[i][j]=dp[i-1][j-1]+dp[i-1][j-2]*2+....dp[i-1][j-k]*k;

这样的复杂度是n*n*n;这样是过不了的；

那么dp[i][j+1]=dp[i-1][j]+dp[i-1][j-1]*2+dp[i-1][j-2]*3+....dp[i-1][j-k+1]*k;

那么dp[i][j+1]=dp[i][j-1]+dp[i-1][j-1]+sum[j-2]-sum[max(0,j-1-m)]-dp[i-1][max(0,j-m-1)]*m;

那么我们每次维护一个dp[i][j]的前缀和就可以了。

#include<stdio.h>
#include<algorithm>
#include<iostream>
#include<string.h>
#include<math.h>
#include<stdlib.h>
#include<queue>
using namespace std;
typedef long long LL;
LL dp[2][15005];
const int mod=100000007;
LL sum[15005];
int main(void)
{
    int i,j,k;
    scanf("%d",&k);
    int s;
    int n,m,c;
    for(s=1; s<=k; s++)
    {
        scanf("%d %d %d",&n,&m,&c);
        memset(dp,0,sizeof(dp));
        memset(sum,0,sizeof(sum));
        for(i=1; i<=m; i++)
        {
            dp[1][i]=i;
            dp[1][i]%=mod;
            sum[i]=(sum[i-1]+dp[1][i])%mod;
        }
        for(i=m+1;i<=c;i++)
            sum[i]=sum[i-1];
        for(i=2; i<=n; i++)
        {
            int uu=(i)%2;
            int kk=(i+1)%2;
            for(j=0; j<i; j++)
            {
                dp[uu][j]=0;
            }
            for(j=i;j<=c; j++)
            {
      dp[uu][j]=((dp[kk][j-1]+dp[uu][j-1])%mod+(sum[j-2]-sum[max(0,j-1-m)])%mod-dp[kk][max(0,j-m-1)]*m%mod)%mod;
                dp[uu][j]%=mod;
                dp[uu][j]+=mod;
                dp[uu][j]%=mod;
            }
            for(j=1; j<=c; j++)
            {
                sum[j]=sum[j-1]+dp[uu][j];
                sum[j]%=mod;
            }
        }
        printf("Case %d: ",s);
        printf("%lld
",(dp[n%2][c]%mod+mod)%mod);
    }
    return 0;
}