Lucas定理的应用

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<algorithm>

using namespace std;

const int maxn=1000100;
const int INF=(1<<29);
const int p=10007;

typedef long long ll;

ll n,m;

ll qpow(ll n,ll k)
{
ll res=1;
for(;k;k>>=1)
{
if(k&1) res=(res%p)*(n%p)%p;
n=(n%p)*(n%p)%p;
}
return res;
}

ll C(ll n,ll k)
{
if(n<k) return 0;
ll res=1;
for(int i=1; i<=k; i++)
{
ll a=(n-k+i)%p;
ll b=i%p;
res=res*(a*qpow(b,p-2)%p)%p;
}
return res%p;
}

ll lucas(ll n,ll k)
{
if(k==0) return 1;
return (C(n%p,k%p)%p)*(lucas(n/p,k/p)%p)%p;
}

int main()
{
while(~scanf("%lld%lld",&n,&m))
{
printf("%lld\n",lucas(m,n));
}
return 0;
}