Quicksort_optimised.java

class QuickSort
{
 int partition(int arr[], int low, int high)
 {
 int pivot = arr[high];
 int i = (low-1); 
 for (int j=low; j<high; j++)
 {
 if (arr[j] <= pivot)
 {
 i++;
 int temp = arr[i];
 arr[i] = arr[j];
 arr[j] = temp;
 }
 }
 int temp = arr[i+1];
 arr[i+1] = arr[high];
 arr[high] = temp;
 
 return i+1;
 }
 void sort(int arr[], int low, int high)
 {
 if (low < high)
 {

 int pi = partition(arr, low, high);
 sort(arr, low, pi-1);
 sort(arr, pi+1, high);
 }
 }
 static void printArray(int arr[])
 {
 int n = arr.length;
 for (int i=0; i<n; ++i)
 System.out.print(arr[i]+" ");
 System.out.println();
 }
 
 public static void main(String args[])
 {
 int arr[] = {10, 7, 8, 9, 1, 5};
 int n = arr.length;
 
 QuickSort ob = new QuickSort();
 ob.sort(arr, 0, n-1);
 
 System.out.println("sorted array");
 printArray(arr);
 }
}