【BZOJ 2982】 combination

【题目链接】

https://www.lydsy.com/JudgeOnline/problem.php?id=2982

【算法】

lucas定理

【代码】

#include<bits/stdc++.h>
using namespace std;
const int P = ;

int n,m,T;
int fac[P],inv[P];

inline int power(int a,int n)
{
        int b = a,res = ;
        while (n)
        {
                if (n & ) res = 1ll * res * b % P;
                b = 1ll * b * b % P;
                n >>= ;
        }
        return res;
}
inline void init()
{
         int i;
        fac[] = ;
        for (i = ; i < P; i++) fac[i] = 1ll * fac[i-] * i % P;
        inv[P-] = power(fac[P-],P-);
        for (i = P - ; i >= ; i--) inv[i]    = 1ll * inv[i+] * (i + ) % P;
}
inline int c(int n,int m)
{
        if (n < m) return ;
        return 1ll * fac[n] * inv[m] % P * inv[n-m] % P;
}
inline int C(int n,int m)
{
        if (m == ) return ;
        else return 1ll * C(n/P,m/P) * c(n%P,m%P) % P;
}

int main()
{

        init();
        scanf("%d",&T);
        while (T--)
        {
                scanf("%d%d",&n,&m);
                printf("%d\n",C(n,m));
        }

        return ;

}