Submission #19393

# Submission time Handle Problem Language Result Execution time Memory
19393 2016-02-24T11:11:31 Z bshnet Σ (kriii4_P2) C++14
100 / 100
16 ms 1720 KB
#include <iostream>
#include <vector>

#define MOD (1000000007)

using namespace std;

int pow(int64_t a, int64_t x) {
	int64_t sq[64];
	int ans = 1;

	sq[0] = (a % MOD);
	for(int i = 1; i <= 64; ++i) {
		if(x & 0x01)
			ans = (ans * sq[i-1]) % MOD;

		x >>= 1;
		if(!x)
			break;

		sq[i] = (sq[i-1] * sq[i-1]) % MOD;
	}

	return ans;
}

int expect(vector<int> &ni, vector<int> &si) {
	int n = ni.size();
	int ans = 0;
	for(int i = 0; i < n; ++i) {
		int64_t e = ((int64_t)si[i] * pow(ni[i], MOD - 2)) % MOD;
		ans = (ans + e) % MOD;
	}
	return ans;
}

int main(void) {
	int M;
	cin >> M;

	vector<int> Ni(M), Si(M);
	for(int i = 0; i < M; ++i) {
		cin >> Ni[i] >> Si[i];
	}

	cout << expect(Ni, Si) << endl;

	return 0;
}
# Verdict Execution time Memory Grader output
1 Correct 12 ms 1720 KB Output is correct
2 Correct 16 ms 1720 KB Output is correct
3 Correct 16 ms 1720 KB Output is correct
4 Correct 10 ms 1720 KB Output is correct
5 Correct 16 ms 1720 KB Output is correct
6 Correct 12 ms 1720 KB Output is correct
7 Correct 11 ms 1720 KB Output is correct
8 Correct 12 ms 1720 KB Output is correct
9 Correct 15 ms 1720 KB Output is correct
10 Correct 14 ms 1720 KB Output is correct
11 Correct 14 ms 1720 KB Output is correct
12 Correct 14 ms 1720 KB Output is correct
13 Correct 14 ms 1720 KB Output is correct
14 Correct 15 ms 1720 KB Output is correct
15 Correct 11 ms 1720 KB Output is correct
16 Correct 15 ms 1720 KB Output is correct
17 Correct 15 ms 1720 KB Output is correct
18 Correct 11 ms 1720 KB Output is correct
19 Correct 12 ms 1720 KB Output is correct
20 Correct 16 ms 1720 KB Output is correct