Submission #20077

#	Time	Username	Problem	Language	Result	Execution time	Memory
20077		sui	Σ (kriii4_P2)	C++14	100 / 100	19 ms	1884 KiB

P2

#define _CRT_SECURE_NO_WARNINGS // scanf(), gets() (needed for Visual C++)

//#define NDEBUG
#include <cassert>

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>
#include <functional>
#include <string>
#include <vector>

#include <queue>
#include <set>
#include <map>
#include <unordered_map>
#include <stack>
#include <deque>

using namespace std;

#define MEMSET(x, WITH) memset(x, (WITH), sizeof(x))
#define FOR(i, E) for(int i=0; i<(E); i++)
#define REP(i, LO, HI) for(int i=(LO); i<=(HI); i++)

#define GETINT(x) scanf("%d", &x)
#define GETDBL(x) scanf("%lf", &x)
#define GETSTR(x) scanf("%s", x)
#define NEWINT(x) int x; scanf("%d", &x)
#define NEWDBL(x) double x; scanf("%lf", &x)
#define NEWLN putchar('\n')

#ifdef _WIN32
#define popcnt __popcnt
#else
#define popcnt __builtin_popcount
#endif

typedef long long ll;
//const ll MOD = 1000000007;
//const double PI = atan(1) * 4;







const ll MOD = 1000000007;

ll powerMod(ll a, ll n) {
	ll ans = 1;
	for (int i=62; i>=0; i--) {
		ans = ans * ans % MOD;
		if ((n>>i)&1)
			ans = ans * a % MOD;
	}
	return ans;
}


ll a[10333];
ll b[10333];


int main() {
	int M; cin >> M;
	FOR(i, M) cin >> b[i] >> a[i];

	/*
	ll numer = 0;
	FOR(i, M) {
		ll prod = a[i];
		FOR(j, M) if (i != j) prod = prod * b[i] % MOD;

		numer = (numer + prod) % MOD;
	}

	ll denom = 1;
	FOR(i, M) denom = denom * b[i] % MOD;

	ll ans = numer * powerMod(denom, MOD-2) % MOD;
	cout << ans << endl;
	*/

	ll ans = 0;
	FOR(i, M) {
		ll term = a[i] * powerMod(b[i], MOD-2) % MOD;
		ans += term;
		ans %= MOD;
	}
	cout << ans << endl;


	return 0;
}

• Subtask 1: 100 / 100