Submission #19402

#	Time	Username	Problem	Language	Result	Execution time	Memory
19402		fredldh	Σ (kriii4_P2)	C++98	100 / 100	8 ms	1084 KiB

P2

#include<stdio.h>
#define M 1000000007
#define mod(a) ((a)%1000000007)
typedef long long int lld;
lld pow(lld a, lld x) {
    if(!x) return 1;
    lld P = pow(a, x/2);
    if(x&1) return mod(a*mod(P*P));
    return mod(P*P);
}
lld inv(lld a) {
    return pow(a, M-2);
}
lld div(lld a, lld b) {
    return mod(a*inv(b));
}
int main() {
    int n;
    scanf("%d", &n);
    lld res = 0;
    for(int i = 0; i < n; ++i) {
        int N, S;
        scanf("%d%d", &N, &S);
        res = mod(res+div(S, N));
    }
    printf("%lld\n", res);
    return 0;
}

• Subtask 1: 100 / 100