Two Pointers or Iterators

sortedSquares.cpp

vector<int> sortedSquares(vector<int>& A) {
    vector<int> res(A.size());
    int left = 0, right = 0;
    
    /*for(int i = 0; i < A.size(); i++){
        if(A[i] < 0){
            
        }
        if(A[i] >= 0){
            right = i; //
            left = right-1;
            break;
        }
    }
    if(A.back() <= 0){
        left = A.size()-1;
        right = left+1;
    }*/
    
    //improvement of above
    while(right < A.size() && A[right] < 0){
        right++;
    }
    left = right-1;
    
    int j = 0;
    while(left >= 0 && right < A.size()){
        int a = A[left] * A[left];
        int b = A[right] * A[right];
        if(a < b){
            res[j++] = a;
            left--;
        }else{
            res[j++] = b;
            right++;
        }
    }
    while(left >= 0){
        int a = A[left] * A[left];
        res[j++] = a;
        left--;
    }
    while(right < A.size()){
        int b = A[right] * A[right];
        res[j++] = b;
        right++;
    }
    return res;
}