Submission #19411

#	Time	Username	Problem	Language	Result	Execution time	Memory
19411		Qwaz	Σ (kriii4_P2)	C++14	100 / 100	7 ms	1084 KiB

P2

#include <cstdio>

typedef long long ll;
const int MOD = 1000000007;

ll modpow(ll a, ll x) {
	ll ret = 1;
	a = a % MOD;

	while (x) {
		if (x & 1) ret = ret * a % MOD;
		a = a * a % MOD;
		x >>= 1;
	}

	return ret;
}

int main() {
	int n;
	scanf("%d", &n);

	ll res = 0;
	for (int i = 0; i < n; i++) {
		int a, b;
		scanf("%d%d", &a, &b);
		res = (res + b * modpow(a, MOD-2)) % MOD;
	}

	printf("%lld\n", res);

	return 0;
}

• Subtask 1: 100 / 100