loj2173 「FJOI2016」建筑师

#include <iostream>
#include <cstdio>
using namespace std;
typedef long long ll;
int T, n, a, b, s[50005][205], c[205][205];
const int mod=1e9+7;
int main(){
    for(int i=0; i<=50000; i++){
        if(i<=200)  s[i][i] = 1;
        for(int j=1; j<=min(i-1, 200); j++)
            s[i][j] = (s[i-1][j-1] + (ll)s[i-1][j]*(i-1)%mod) % mod;
    }
    for(int i=0; i<=200; i++){
        c[i][0] = 1;
        for(int j=1; j<=i; j++)
            c[i][j] = (c[i-1][j-1] + c[i-1][j]) % mod;
    }
    cin>>T;
    while(T--){
        scanf("%d %d %d", &n, &a, &b);
        printf("%d\n", (ll)s[n-1][a+b-2]*c[a+b-2][a-1]%mod);
    }
    return 0;
}