题解 | 【模板】分数取模

#include<iostream>
#include<algorithm>
using namespace std;

typedef long long ll;

const ll p = 1000000007;

ll fast_pow_mod(ll base, ll exp, ll p) {
	if (base == 0) return 0;
	else if (exp == 0 || base == 1) return 1;
	
	ll result = 1;
	while (exp > 0) {
		if (exp & 1) {
			result = (result * base) % p;  
		}
		base = (base * base) % p;
		exp >>= 1;
	}
	return result;	
} 

int main() {
	ll n, a, b;
	cin >> n;
	while(n-- > 0) {
		cin >> a >> b;
	  	//处理a < 0的情况
		a = a % p;
		a = a > 0 ? a : a + p;
		//求b ^ (p - 2) mod p
		cout<< (a * fast_pow_mod(b, p - 2, p)) % p <<endl;
	} 	
}