Particle Accelerator II

#pragma GCC optimize("O3,unroll-loops")

#include <bits/stdc++.h>
using namespace std;

#define int long long
#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef long double ld;

void solve() {
    int n;
    cin >> n;

    vi a(n);
    for (int i = 0; i < n; i++) {
        cin >> a[i];
    }

    sort(all(a));
    reverse(all(a));

    int cur = a[0];
    int ans = 0;
    for (int i = 1; i < n; i++) {
        ans += cur * a[i];
        cur += a[i];
    }
    cout << ans << '\n';
}

signed main() {
    cin.tie(0)->sync_with_stdio(0);
    cin.exceptions(cin.failbit); // RTE if input wrong datatype
    
    int t = 1;
    // cin >> t; 

    while (t--) {
        solve();
    }
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED