Submission #19328

#	Time	Username	Problem	Language	Result	Execution time	Memory
19328		xdoju	Σ (kriii4_P2)	C++14	100 / 100	6 ms	1084 KiB

P2

#include <cstdio>
using namespace std;

const long long MOD = 1000000007ll;

long modpow(long long r, long long n) {
	long long ret = 1;
	while (n > 0) {
		if (n % 2 > 0) {
			ret = (ret * r) % MOD;
		}
		r = (r * r) % MOD;
		n /= 2;
	}
	return ret;
}

long long modinv(int n) {
	return modpow(n, MOD - 2);
}

void proc() {
	int m;
	scanf("%d", &m);
	long long res = 0;
	for (int i = 0; i < m; ++i) {
		int face, sum;
		long long u = 1;
		scanf("%d %d", &face, &sum);
		u = (u * sum) % MOD;
		u = (u * modinv(face)) % MOD;
		res = (res + u) % MOD;
	}
	printf("%lld", res);
}

int main() {
	proc();
	return 0;
}

• Subtask 1: 100 / 100