3SUM

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;

int main(){
    ull n, x;
    cin >> n >> x;

    vector<ll> as;
    vector<ll> as2;
    map<ll, ll> h;

    as.reserve(n);
    as2.reserve(n);

    for(ull i=0; i<n; i++){
        ll a;
        cin >> a;
        as.push_back(a);
    }

    for(ull i=0; i<n; i++){
        h[x - as[i]] = as[i];
    }

    for(ull i=0; i<n; i++){
        for(ull j=0; j<n; j++){
            ll ts = as[i] + as[j];
            if(h.count(ts) && h[ts] != as[i] && h[ts] != as[j]){
                cout << h[ts] << " " << as[i] << " " << as[j] << endl;
                return 0;
            }
        }
    }
    cout << "IMPOSSIBLE" << endl;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: WRONG ANSWER

Test 3

Verdict: ACCEPTED

Test 4

Verdict: WRONG ANSWER

Test 5

Verdict: WRONG ANSWER

Test 6

Verdict: WRONG ANSWER

Test 7

Verdict: WRONG ANSWER

Test 8

Verdict: WRONG ANSWER

Test 9

Verdict: WRONG ANSWER

Test 10

Verdict: ACCEPTED

Test 11

Verdict: WRONG ANSWER

Test 12

Verdict: WRONG ANSWER

Test 13

Verdict: TIME LIMIT EXCEEDED

Test 14

Verdict: TIME LIMIT EXCEEDED

Test 15

Verdict: TIME LIMIT EXCEEDED

Test 16

Verdict: WRONG ANSWER

Test 17

Verdict: WRONG ANSWER

Test 18

Verdict: WRONG ANSWER

Test 19

Verdict: ACCEPTED

Test 20

Verdict: WRONG ANSWER

Test 21

Verdict: ACCEPTED

Test 22

Verdict: TIME LIMIT EXCEEDED

Test 23

Verdict: ACCEPTED