Summat

input/code.cpp: In function 'int main()':
input/code.cpp:25:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         while(ans.size() < n){
               ~~~~~~~~~~~^~~

#include <iostream>
#include <vector>
#include <cassert>
#include <set>
//#include "stdlib_printing.hh"

typedef long long LL;

using namespace std;

int main(){
    LL n; cin >> n;
    multiset<LL> B;
    for(LL i = 0; i < n*(n-1)/2; i++){
        LL x; cin >> x; B.insert(x);
    }
    vector<LL> Bvec(B.begin(), B.end());
    
    for(LL j = 2; j < n*(n-1)/2; j++){
        LL a1 = Bvec[0] + Bvec[1] - Bvec[j];
        if(a1 % 2 == 1) continue; else a1 /= 2;
        vector<LL> ans;
        multiset<LL> M = B;
        ans.push_back(a1);
        while(ans.size() < n){
            LL b = *M.begin();
            LL a = b - a1;
            for(LL x : ans){
                if(M.count(x + a) == 0) goto tryagain;
                M.erase(M.find(x+a));
            }
            ans.push_back(a);
        }
        for(auto x : ans) cout << x << " ";
        cout << "\n";
        return 0;
        tryagain: ;
    }

}

Test 1

Group: 1, 2, 3

Verdict: ACCEPTED

Test 2

Group: 1, 2, 3

Verdict: ACCEPTED

Test 3

Group: 1, 2, 3

Verdict: ACCEPTED

Test 4

Group: 1, 2, 3

Verdict: ACCEPTED

Test 5

Group: 1, 2, 3

Verdict: ACCEPTED

Test 6

Group: 2, 3

Verdict: ACCEPTED

Test 7

Group: 2, 3

Verdict: ACCEPTED

Test 8

Group: 2, 3

Verdict: ACCEPTED

Test 9

Group: 2, 3

Verdict: ACCEPTED

Test 10

Group: 2, 3

Verdict: ACCEPTED

Test 11

Group: 3

Verdict: ACCEPTED

Test 12

Group: 3

Verdict: ACCEPTED

Test 13

Group: 3

Verdict: ACCEPTED

Test 14

Group: 3

Verdict: ACCEPTED

Test 15

Group: 3

Verdict: ACCEPTED