Submission #20154

#	Time	Username	Problem	Language	Result	Execution time	Memory
20154		veckal	Σ (kriii4_P2)	C11	100 / 100	8 ms	1084 KiB

P2

#include <stdio.h>
#define MOD 1000000007
typedef long long ll;

ll pow(ll base, ll exp) {
    if (exp == 1) return base;
    ll ret = pow(base, exp>>1);
    ret = (ret * ret) % MOD;
    if (exp&1) ret = (ret * base) % MOD;
    return ret;
}

ll inv(ll a) {
    return pow(a, MOD-2);
}

int m, n, s, i;
int ans;

int main() {
    scanf("%d", &m);
    for (i=0; i<m; ++i) {
        scanf("%d%d", &n, &s);
        ans = (ans + (inv(n) * s) % MOD) % MOD;
    }
    printf("%d\n", ans);
    return 0;
}

• Subtask 1: 100 / 100