【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 = 10007;

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

inline int power(int a,int n)
{
        int b = a,res = 1;
        while (n)
        {
                if (n & 1) res = 1ll * res * b % P;
                b = 1ll * b * b % P;
                n >>= 1;
        }
        return res;
}
inline void init()
{
         int i;
        fac[0] = 1; 
        for (i = 1; i < P; i++) fac[i] = 1ll * fac[i-1] * i % P;
        inv[P-1] = power(fac[P-1],P-2);
        for (i = P - 2; i >= 0; i--) inv[i]    = 1ll * inv[i+1] * (i + 1) % P;    
} 
inline int c(int n,int m)
{
        if (n < m) return 0;
        return 1ll * fac[n] * inv[m] % P * inv[n-m] % P; 
} 
inline int C(int n,int m)
{
        if (m == 0) return 1;
        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
",C(n,m));
        }
        
        return 0;
    
}