light oj 1095 组合数学

 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
 #include <math.h>
 #include <iostream>
 #include <algorithm>
 #include <climits>
 #include <queue>
 #define ll long long

 using namespace std;

 const int MAX = ;
 const ll MOD = 1e9+;
 ll F[],C[][];

 void init()
 {
     F[] = ;
     F[] = ;
     F[] = ;
     for(int i = ; i <= ; i++)
         F[i] = (i-)*(F[i-]+F[i-])%MOD;

     for(int i = ; i <= ; i++)
     {
         for(int j = ; j <= i; j++)
         {
             if(j == )
                 C[i][j] = ;
             else
                 C[i][j] = (C[i-][j]+C[i-][j-])%MOD;
         }
     }
 }

 void solve()
 {
     int n,m,k;
     scanf("%d %d %d",&n,&m,&k);
     ll ans = ;
     for(int i = ; i <= n-m; i++)
     {
         ans += (C[n-m][i]*F[n-k-i]);
         ans %= MOD;
     }
     ans *= C[m][k];
     ans %= MOD;
     printf("%lld\n",ans);
 }

 int main(void)
 {
     init();
     int t,cnt = ;
     scanf("%d",&t);
     while(t--)
     {
         printf("Case %d: ",++cnt);
         solve();
     }
     return ;
 }