быстрая сортировка

#include <iostream>
#include <cmath>
#include <algorithm>
#include<cstdlib>

using namespace std;


void quick_sort (int *A, int first, int last)
{
int x, i, j, c = first, d = last;

while (c < d)
{
  int m = (c+d)/2;

 if (A[c] > A[d] && A[c] < A[m])
 x = A[c];
  else if (A[d] > A[c] && A[d] < A[m])
   x = A[d];
    else x = A[m];

 i = c;
 j = d;

   while (i < j)
   {
    while (A[i] < x)
     i++;
    while (A[j] > x)
     j--;

    if (i <= j)
     {
       swap(A[i], A[j]);
       i++;
       j--;
     }
   }

if (j-c < d-i)
 {
   if (c < j)
    quick_sort(A,c,j);
    c = i;
 }
else
 {
   if (i<d)
   quick_sort(A,i,d);
   d = j;
 }
}
}

int main ()
{
  int n;
  cin >> n;
  int *arr = new int[n];

  for (int i=0; i<n; i++)
  cin >> arr[i];

  quick_sort(arr, 0, n-1);

  for (int i=0; i<n; i++)
  cout << arr[i] << " ";
}