2023-9-8 求组合数(三)

题目链接：求组合数 III

#include 
#include 

using namespace std;

typedef long long LL;

int p;

int qmi(int a, int k)
{
    int res = 1;
    while(k)
    {
        if(k & 1) res = (LL) res * a % p;
        k >>= 1;
        a = (LL) a * a % p;
    }
    return res;
}

int C(int a, int b)
{
    int res = 1;
    for(int i = 1, j = a; i <= b; i++, j--)
    {
        res = (LL) res * j % p;
        res = (LL) res * qmi(i, p - 2) % p;
    }
    return res;
}

int lucas(LL a, LL b)
{
    if(a < p && b < p) return C(a, b);
    return (LL)C(a % p,  b % p) * lucas(a / p, b / p) % p;
}

int main()
{
    
    int n;
    cin >> n;
    
    while(n--)
    {
        LL a, b;
        cin >> a >> b >> p;
        cout << lucas(a, b) << endl;
    }
    
    return 0;
}
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