Submission #19247

#	Time	Username	Problem	Language	Result	Execution time	Memory
19247		gs14004	Uniting (kriii2_U)	C++14	4 / 4	10 ms	1116 KiB

U

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <limits.h>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <algorithm>
#include <string>
#include <functional>
#include <vector>
#include <numeric>
#include <deque>
#include <utility>
#include <bitset>
#include <assert.h>
#include <iostream>
using namespace std;
typedef long long lint;
typedef long double llf;
typedef pair<int, int> pi;
const int mod = 1e9 + 7;
int n, a[100005];

int main(){
	scanf("%d",&n);
	lint s = 0, sc = 0, fc = 1;
	for(int i=0; i<n; i++){
		scanf("%d",&a[i]);
		s += a[i];
		sc += a[i] * a[i];
	}
	for(int i=2; i<=n; i++){
		fc *= (1ll * i * (i-1)) % mod;
        fc %= mod;
	}
	s = (s * s - sc) / 2;
	printf("%lld\n%lld",s,fc);
}

Compilation message (stderr)

U.cpp: In function 'int main()':
U.cpp:28:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   28 |  scanf("%d",&n);
      |  ~~~~~^~~~~~~~~
U.cpp:31:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   31 |   scanf("%d",&a[i]);
      |   ~~~~~^~~~~~~~~~~~

• Subtask 1: 4 / 4