Interview Sort Function

QuickSort

Java Code:

 1 import java.util.*;
 2 public class quickSort{
 3     public static void main(String [] args){
 4         int [] arr = new int[]{4,2,7,5,0,9,1};
 5         int low = 0;
 6         int high = arr.length-1;
 7         quickSort(arr, low, high);
 8         System.out.println(Arrays.toString(arr));
 9     }
10
11     private static void quickSort(int [] arr, int low, int high){
12         if(arr == null || arr.length == 0){
13             return;
14         }
15
16         if(low >= high){
17             return;
18         }
19
20         int pivot = arr[low + (high - low)/2];
21
22         //make left < pivot, right > pivot
23         int i = low;
24         int j = high;
25         while(i <= j){
26             while(arr[i] < pivot){
27                 i++;
28             }
29             while(arr[j] > pivot){
30                 j--;
31             }
32
33             if(i <= j){
34                 int temp = arr[i];
35                 arr[i] = arr[j];
36                 arr[j] = temp;
37                 i++;
38                 j--;
39             }
40         }
41
42         //recursively sort two sub arrays
43         quickSort(arr, low, j);
44         quickSort(arr, i, high);
45     }
46 }