c语言 组合数学+大数取模

//hdu5894

#include<iostream>#include<algorithm>#include<cstring>#include<cmath>#include<cstdio>#include<string>#include<set>#include<map>#include<queue>#include<stack>using namespace std;#define LL long long#define N 1000000009#define cl(a,b) memset(a,b,sizeof(a))const int mod=1000000007;LL pow_mod(LL a,int n){    LL ans=1;    while(n)    {        if(n&1)ans=ans*a%mod;        a=a*a%mod;        n>>=1;    }    return ans;}LL C(int n,int m){    if(m>n)return 0;    LL ans=1;    for(int i=1;i<=m;i++)        ans=ans*((n+i-m)*pow_mod(i,mod-2)%mod)%mod;    return ans;}int main(){    int t;    LL n,m,k;    scanf("%d",&t);    while(t--)    {        scanf("%I64d%I64d%I64d",&n,&m,&k);        if(m==1)printf("%I64d\n",n);        else        printf("%I64d\n",(C(n-k*m-1,m-1)*n%mod)*pow_mod(m,mod-2)%mod);//C*n/m除号改成*pow_mod(m,mod-2)    }    return 0;}