Lucas定理模板題目

#include <iostream>
#include <string.h>
#include <cmath>
#define ll long long
using namespace std;
const int maxn=10000007;
ll n,m,p;
ll fac[maxn];
 
void getfac(ll p)//預處理階層
{
    fac[0]=1;
    for(int i=1;i<=p;i++)
        fac[i]=fac[i-1]*i%p;
}
 
ll power(ll a,ll n,ll p)
 
//快速冪運算
{
    ll ans=1;
    while(n)
    {
        if(n&1)
            ans=ans*a%p;
        a=a*a%p;
        n/=2;
    }
    return ans;
}
 
ll lucas(ll n,ll m,ll p)
{
    ll ans=1;
    while(n&&m)
    {
        ll a=n%p;
        ll b=m%p;
        if(a<b) return 0;
        ans
 
=(ans*fac[a]*power(fac[b]*fac[a-b]%p,p-2,p))%p;//  fac[b]*fac[a-b]後面別忘了%p，否則WA
        n/=p;
        m/=p;
    }
    return ans;
}
 
 
int main()
{
    int t;cin>>t;
    getfac(10007);
    while(t--)
    {
        cin>>n>>m;
        cout<<lucas(n,m,10007)<<endl;
    }
    
 
return 0;
}

BZOJ 2982 combination