Submission #9684

#	Time	Username	Problem	Language	Result	Execution time	Memory
9684		shashack	Uniting (kriii2_U)	C++98	1 / 4	28 ms	9364 KiB

U

#include<iostream>
using namespace std;

int main(){
	int n; cin >> n;
	long long val[1000000+1];
	for (int i = 0; i < n; i++){
		cin >> val[i];
	}
	long long ret = 0;
	for (int i = 1; i < n; i++){
		ret += val[i] * val[i - 1];
		val[i] = val[i] + val[i - 1];
	}
	int count = 1;
	for (int i = n; i >= 2; i--){
		count = (((count % 1000000007) * (i) % 1000000007) * (i - 1)) % 1000000007;
	}
	cout << ret << endl << count << endl;
}

• Subtask 1: 1 / 4