735

class Solution {
public:
    vector<int> asteroidCollision(vector<int>& asteroids) {
        vector<int> state;
        for(int i=0; i<asteroids.size(); i++){
            bool flag = false;
            if(asteroids[i] > 0){
                state.push_back(asteroids[i]);
                continue;
            }
            while(!flag && !state.empty() && state.back() > 0 && -state.back() >= asteroids[i]){
                if(-state.back() == asteroids[i]) flag = true;
                state.pop_back();
            }
            if(flag) continue;
            if(!state.empty() && state.back() > 0 && -state.back() < asteroids[i])
                continue;
            else
                state.push_back(asteroids[i]);
        }
        return state;
    }
};