제출 #19332

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
19332		exqt	Σ (kriii4_P2)	C++98	100 / 100	28 ms	2000 KiB

P2

#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <utility>
#include <queue>
#include <string>
#include <cstring>
#include <map>
using namespace std;

#define in cin
#define out cout
#define ll long long int

ll DV = 1000000007;
ll mypow(ll a, ll b)
{
    ll t = a;
    ll res = 1;
    while(b)
    {
        if(b%2) res = (res * t) % DV;
        t = t % DV;
        t = (t*t) % DV;
        b = b >> 1;
    }

    return res;
}

ll myinv(ll a)
{
    return mypow(a, DV-2);
}

int main()
{
    int n; in >> n;
    ll mb = 1;
    vector<ll> va, vb;
    for(int i=0; i<n; i++)
    {
        ll a, b; in >> b >> a;
        va.push_back(a);
        vb.push_back(b);
        mb *= b; mb %= DV;
    }

    ll u = 0;
    for(int i=0; i<n; i++)
    {
        u += ((va[i]%DV)*(mb%DV)%DV)*(myinv(vb[i])%DV);
        u %= DV;
    }

    out << (u)*(myinv(mb))%DV;

    return 0;
}

• Subtask 1: 100 / 100