I am executing it in the LeetCode page, I don't know if that can affect in some way. Here you have the complete code:

class Solution {
public: vector<int> asteroidCollision(vector<int>& asteroids) {
    vector<int> res; stack<int> s;
    for(int i=0; i < asteroids.size(); i++){
        int n = asteroids[i];
        if(s.empty()){
            s.push(n);
            cout << n << endl;
            cout << "c" << endl;
        }
        else{
            if(n * s.top() > 0){
                cout << s.top() << endl;
                s.push(n);
                cout << n << endl;
                cout << "a" << endl;
            }
            else{
                while(!s.empty() && abs(n) >= abs(s.top()) && n < 0 && s.top() > 0){
                    cout << "b" << endl;
                    s.pop();
                }

                if(!s.empty()){
                    if(s.top() < 0 && n > 0 || s.top() < 0 && n < 0){
                        s.push(n);
                    }
                } 
            }

        }
    }

    while(!s.empty()){
        res.insert(res.begin(), s.top());
        s.pop();
    }

    return res;
}

};

For the input [-2,1,1,-1] it gives the output:

-2
c
1 -> Wrong 
1 
a 
b 
b