Interview Sort Function

QuickSort

Java Code:

 import java.util.*;
 public class quickSort{
     public static void main(String [] args){
         int [] arr = new int[]{4,2,7,5,0,9,1};
         int low = 0;
         int high = arr.length-1;
         quickSort(arr, low, high);
         System.out.println(Arrays.toString(arr));
     }

     private static void quickSort(int [] arr, int low, int high){
         if(arr == null || arr.length == 0){
             return;
         }

         if(low >= high){
             return;
         }

         int pivot = arr[low + (high - low)/2];

         //make left < pivot, right > pivot
         int i = low;
         int j = high;
         while(i <= j){
             while(arr[i] < pivot){
                 i++;
             }
             while(arr[j] > pivot){
                 j--;
             }

             if(i <= j){
                 int temp = arr[i];
                 arr[i] = arr[j];
                 arr[j] = temp;
                 i++;
                 j--;
             }
         }

         //recursively sort two sub arrays
         quickSort(arr, low, j);
         quickSort(arr, i, high);
     }
 }