【Gym 100947E】Qwerty78 Trip（组合数取模/费马小定理）

#include<bits/stdc++.h>
#define N 200005
#define M 1000000007
#define ll long long
using namespace std;
ll n,m,t,x,y,fac[N]= {1};
ll qpow(ll a,ll b)
{
    ll ans=1;
    ll k=a;
    while(b)
    {
        if(b&1)ans=ans*k%M;
        k=k*k%M;
        b>>=1;
    }
    return ans;
}
ll C(ll n,ll m)
{
    if(m>n)return 0;
    return fac[n]*qpow(fac[m],M-2)%M*qpow(fac[n-m],M-2)%M;
}
int main()
{
    for(int i=1; i<N; i++)fac[i]=fac[i-1]*i%M;
    scanf("%d",&t);
    while(t--)
    {
        scanf("%d%d%d%d",&n,&m,&x,&y);
        printf("%lld\n",((C(n+m-2,n-1)-C(x+y-2,x-1)*C(n-x+m-y,n-x)%M+M)%M));
    }
    return 0;
}