3SUM

input/code.cpp: In function 'int main()':
input/code.cpp:28:37: warning: comparison of integer expressions of different signedness: 'std::map<long long int, int>::mapped_type' {aka 'int'} and 'ull' {aka 'long long unsigned int'} [-Wsign-compare]
   28 |             if(h.count(ts) && h[ts] != i && h[ts] != j && j != i){
input/code.cpp:28:51: warning: comparison of integer expressions of different signedness: 'std::map<long long int, int>::mapped_type' {aka 'int'} and 'ull' {aka 'long long unsigned int'} [-Wsign-compare]
   28 |             if(h.count(ts) && h[ts] != i && h[ts] != j && j != i){

#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;
    map<ll, int> h;

    as.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]] = 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] != i && h[ts] != j && j != i){
                cout << (h[ts]+1) << " " << (i+1) << " " << (j+1) << endl;
                // cout << std::get<0>(h[ts]) << " " << i << " " << j << endl;
                return 0;
            }
        }
    }
    cout << "IMPOSSIBLE" << endl;
}

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: TIME LIMIT EXCEEDED

Test 14

Verdict: TIME LIMIT EXCEEDED

Test 15

Verdict: TIME LIMIT EXCEEDED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED

Test 22

Verdict: TIME LIMIT EXCEEDED

Test 23

Verdict: ACCEPTED