Submission #19313

#	Time	Username	Problem	Language	Result	Execution time	Memory
19313		imsifile	Σ (kriii4_P2)	C++98	100 / 100	8 ms	1084 KiB

P2

#include<stdio.h>
#define mod 1000000007

typedef long long lld;
lld a, b, sum;

lld exp(lld a, lld b){
	if(b==0)return 1;
	lld k=exp(a, b/2);
	k=(k*k)%mod;
	if(b%2)k=(k*a)%mod;
	return k;
}

int main(){
	int n, i;
	scanf("%d", &n);
	for(i=0; i<n; i++){
		scanf("%lld%lld", &a, &b), a=exp(a,mod-2);
		sum = (sum + a*b)%mod;
	}
	printf("%lld", sum);
	return 0;
}

• Subtask 1: 100 / 100