Submission #9838

#	Time	Username	Problem	Language	Result	Execution time	Memory
9838		effserv	Uniting (kriii2_U)	C++98	1 / 4	12 ms	1088 KiB

U

#include <cstdio>

using namespace std;

typedef long long ll;

int main()
{
	int N;
	scanf("%d", &N);

	ll a;
	scanf("%lld", &a);

	ll A = (ll)a;
	ll C = 0;

	for (int i = 0; i < N - 1; i++)
	{
		scanf("%lld", &a);
		C += A*a;
		A += a;
	}

	printf("%lld\n0", C);

	return 0;
}

• Subtask 1: 1 / 4