【CF1478C】Nezzar and Symmetric Array

code

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <cstring>

using namespace std;
typedef long long ll;

int n;
void solve(){
    cin >> n;
    vector<ll> v;
    for (int i = 0; i < 2 *n; ++i) {
        ll x;
        cin >> x;
        v.push_back(x);
    }
    sort(v.rbegin(), v.rend());
    v.erase(unique(v.begin(), v.end()), v.end());
    if (v.size() != n){
        cout << "NO\n";
        return;
    }
    int div = n << 1;
    vector<ll> a;
    a.push_back(0);

    for (int i = 0; i < n; ++i) {
        ll sum = v[i];
        if (i >= 1) a[i] += a[i - 1];
        sum -= 2*a[i];
        if (sum > 0 && sum % div == 0){
            a.push_back(sum / div);
            div -= 2;
        }else{
            cout << "NO\n";
            return;
        }
    }
    cout << "YES\n";
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(), cout.tie();
    int cases;
    cin >> cases;
    while (cases--){
        solve();
    }
    return 0;
}

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