3SUM

#include <iostream>
#include <vector>

int main() {
    int n, x;
    std::cin >> n >> x;
    std::vector<int> array(n);
    for (int i = 0; i < n; ++i) {
        std::cin >> array[i];
    }

    if (array.size() < 3) {
        std::cout << "IMPOSSIBLE\n";
    } else {
        int sol_i = 0, sol_j = 0, sol_k = 0;
        bool flag = false;
        for (int i = 0; i < n - 2 && !flag; ++i) {
            for (int j = i + 1; j < n - 1 && !flag; ++j) {
                for (int k = j + 1; k < n; ++k) {
                    if (array[i] + array[j] + array[k] == x) {
                        sol_i = i + 1;
                        sol_j = j + 1;
                        sol_k = k + 1;
                        flag = true;
                        break;
                    }
                }
            }
        }

        if (sol_i == sol_j && sol_j == sol_k) {
            std::cout << "IMPOSSIBLE\n";
        } else {
            std::cout << sol_i << " " << sol_j << " " << sol_k << "\n";
        }
    }
    return 0;
}

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: TIME LIMIT EXCEEDED

Test 11

Verdict: TIME LIMIT EXCEEDED

Test 12

Verdict: TIME LIMIT EXCEEDED

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: TIME LIMIT EXCEEDED

Test 19

Verdict: TIME LIMIT EXCEEDED

Test 20

Verdict: TIME LIMIT EXCEEDED

Test 21

Verdict: TIME LIMIT EXCEEDED

Test 22

Verdict: TIME LIMIT EXCEEDED

Test 23

Verdict: ACCEPTED