Submission #9419

#	Time	Username	Problem	Language	Result	Execution time	Memory
9419		hodduc	Uniting (kriii2_U)	C++98	1 / 4	12 ms	1868 KiB

U

#include<stdio.h>
long long a, b;
int num[100001];
int d[100001];
int N;
int main()
{
	scanf("%d", &N);
	for(int i = 0; i < N; i++) scanf("%d", &num[i]);
	// sum
	long long sum = num[0];
	for(int i = 1; i < N; i++)
	{
		a += sum * num[i];
		sum += num[i];
	}
	printf("%lld\n", a);

	d[1] = 1;
	long long tmp = 0;
	for(int i = 2; i <= N; i++){
		tmp = d[i-1];
		tmp *= i;
		tmp *= i-1;
		tmp %= 1000000007;
		d[i] = tmp;
	}
	printf("%d\n", d[N]);
}

• Subtask 1: 1 / 4