DailyProblem/collision.cpp at main · Inferno-coder/DailyProblem · GitHub

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class Solution {
public:
    vector<int> asteroidCollision(vector<int>& asteroids) {
        int n = asteroids.size();
        stack<int> stk;

        for(int i = 0; i < n; i++){
            if(stk.empty() || asteroids[i] > 0){
                stk.push(asteroids[i]);
            }else{
                while(!stk.empty() && stk.top() > 0 && stk.top() < abs(asteroids[i])){
                    stk.pop();
                }

                if(!stk.empty() && stk.top() == abs(asteroids[i])){
                    stk.pop();
                }else{
                    if(stk.empty() || stk.top() < 0){
                        stk.push(asteroids[i]);
                    }
                }
            }
        }
        vector<int> ans(stk.size(), 0);
        int size = stk.size();
        while(!stk.empty()){
            ans[--size] = stk.top();
            stk.pop();
        }
        return ans;
    }
};