Problem C. 欧皇 ————2019.10.12

题目：

再次感激土蛋

 #include <bits/stdc++.h>
 
 using namespace std;
 
 typedef long long ll;
 const ll mod = 1e9 + ;
 ll C[][];
 
 void pre(){
     C[][] = ;
     for(int i = ; i <= ; i ++){
         C[i][] = ;
         for(int j = ; j <= i; j ++){
             C[i][j] = (C[i - ][j - ] + C[i - ][j]) % mod;
         }
     }
 }
 int n, m, c;
 int a[];
 ll f[][][];
 ll g[][][], h[][][];
 int main(){
     freopen("europe.in", "r", stdin);
     freopen("europe.out", "w", stdout);
 
     scanf("%d%d%d", &n, &m, &c);
     for(int i = ; i <= c; i ++){
         scanf("%d", &a[i]);
     }
     pre();
     for(int k = ; k <= c; k ++){
         for(int i = ; i <= n; i ++){
             for(int j = ; j <= m; j ++){
                 h[k][i][j] = C[i * j][a[k]];
                 ll flag = -;
                 for(int jj = j - ; jj >= ; jj --){
                     h[k][i][j] = (h[k][i][j] + C[j][jj] * C[i * jj][a[k]] % mod * flag + mod) % mod;
                     flag = -flag;
                 }
             }
         }
     }
     for(int k = ; k <= c; k ++){
         for(int j = ; j <= m; j ++){
             for(int i = ; i <= n; i ++){
                 g[k][i][j] = h[k][i][j];
             //  printf("%d %d %d %lld\n", k, i, j, g[k][i][j]);
                 ll flag = -;
                 for(int ii = i - ; ii >= ; ii --){
                     g[k][i][j] = (g[k][i][j] + C[i][ii] * h[k][ii][j] % mod * flag + mod) % mod;
                     flag = -flag;
                 }
             //  printf("%d %d %d %lld\n", k, i, j, g[k][i][j]);
             }
         }
     }
     f[][][] = ;
     for(int k = ; k <= c; k ++){
         for(int i = ; i <= n; i ++){
             for(int j = ; j <= m; j ++){
                 for(int ii = ; ii <= i - ; ii ++){
                     for(int jj = ; jj <= j - ; jj ++){
                         if((i - ii) * (j - jj) < a[k]) continue;
                         f[k][i][j] = (f[k][i][j] + C[i][i - ii] * C[j][j - jj] % mod * f[k - ][ii][jj] % mod * g[k][i - ii][j - jj]) % mod;
                     }
                 }
             }
         }
     }
     ll ans = ;
     for(int i = ; i <= n; i ++){
         for(int j = ; j <= m; j ++){
             ans = (ans + C[n][i] * C[m][j] % mod * f[c][i][j]) % mod;
         }
     }
     //printf("%d %d %d\n", n, m, c);
     printf("%lld\n", ans);
     return ;
 }