3SUM

input/code.cpp: In function 'bool find_summmands(std::vector<long unsigned int>&, uint64_t, int, int, std::vector<int>&)':
input/code.cpp:9:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long unsigned int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    9 |     if (pos == numbers.size()) return false;
      |         ~~~~^~~~~~~~~~~~~~~~~

#include <iostream>
#include <vector>
#include <cstdint>

bool find_summmands(std::vector<uint64_t> &numbers, uint64_t goal, int count, int pos, std::vector<int> &summands) {
    if (count == 0 && goal != 0) return false;
    if (count == 0 && goal == 0) return true;
    
    if (pos == numbers.size()) return false;

    summands.push_back(pos+1);
    bool success = find_summmands(numbers, goal-numbers[pos], count-1, pos+1, summands);
    if (success) return true;
    summands.pop_back();

    success = find_summmands(numbers, goal, count, pos+1, summands);
    if (success) return true;
    
    return false;
}

int main() {
    int n;
    uint64_t x;
    std::cin >> n >> x;

    std::vector<uint64_t> numbers(n);
    for (auto &number : numbers) {
        std::cin >> number;
    }

    std::vector<int> summands;
    bool success = find_summmands(numbers, x, 3, 0, summands);
    if (!success) {
        std::cout << "IMPOSSIBLE" << std::endl;
        return 0;
    }
    for (auto summand : summands) {
        std::cout << summand << " ";
    }
}

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: TIME LIMIT EXCEEDED

Test 17

Verdict: TIME LIMIT EXCEEDED

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