Submission #74771839

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Source Code Expand

#include<bits/stdc++.h>
#include<atcoder/all>
using namespace atcoder;
using namespace std;
using ll = long long;
using ull = unsigned long long;
using mint = modint1000000007;
#define nl '\n'
#define all(a) (a).begin(), (a).end()
#define rep(i, n) for(ll i = 0; i < (ll)(n); ++i)
template<typename T> bool chmin(T& a, T b){if(a > b){a = b; return true;} return false;}
template<typename T> bool chmax(T& a, T b){if(a < b){a = b; return true;} return false;}
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
const ull BigPrime = (1LL << 61) - 1;
const ll INF = (1LL << 60);
//--------------------------------------------------------------------------------
//--------------------------------------------------------------------------------


void solve()
{
    int n; cin >> n;
    vector<ll> a(n);
    rep(i, n) cin >> a[i];
    sort(all(a));
    vector<ll> imos(n);
    imos[0] = a[0];
    for(int i = 1; i < n; ++i) imos[i] = imos[i-1] + a[i];
    ll ans = 0;
    rep(i, n) ans += (i) * a[i] - (i == 0 ? 0 : imos[i-1]) + imos[n-1] - imos[i] - a[i] * (n-1-i);
    cout << ans / 2 << nl;
}

//--------------------------------------------------------------------------------

int main()
{
    //cout << fixed << setprecision(10); //Be careful!
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    solve();
    return 0;
}

Submission Info

Judge Result