XDU 1032

#include<cstdio>
typedef long long ll;
const ll mod=10007;

ll feima(ll a,ll b)
{
    ll c=1;
    while(b)
    {
        if(b&1)
            c=c*a%mod;
        a=a*a%mod;
        b=b>>1;
    }
    return c;
}
ll C(ll a,ll b)
{
    if(a<b) return 0;
    if(a==b)    return 1;
    if(b>a-b)   b=a-b;
    ll ca=1,cb=1;
    for(ll i=0;i<b;i++)
    {
        ca=ca*(a-i)%mod;
        cb=cb*(b-i)%mod;
    }
    return ca*feima(cb,mod-2)%mod;
}
/*LL Lucas(LL n,LL m)  
{  
    if(m==0) return 1;  
    return C(n%p,m%p)*Lucas(n/p,m/p)%p;  
}*/ 
ll Lucas(ll n,ll m)
{
    ll ans=1;
    while(n&&m&&ans)
    {
        ans=ans%mod*C(n%mod,m%mod)%mod;
        n/=mod;
        m/=mod;
    }
    return ans;
}

int main()
{
    ll n,m;
    while(~scanf("%lld%lld",&n,&m))
        printf("%lld
",Lucas(m,n));
    return 0;
}
原文地址:https://www.cnblogs.com/freinds/p/6292094.html