Rearrange +ve and -ve elements in an array

9.cpp

// Use parititon method of quick sort 

void quick_sort(vector<int> v){
  int i=-1;
  for(int j=0; j<n; j++){
    if(a[j] < 0){
      i++;
      swap(a[i],a[j]);
    }
  }
  
  int neg = 0, pos = i+1;
  
  while(pos < n && neg < pos && a[neg] < 0){
    swap(a[pos], a[neg]);
    neg = neg + 2;
    pos = pos + 1;
  }
}