data/train/rghvgrv/Simple-Programs/Java-Programs/QuickSort.java

import java.util.*;
class QuickSort { 
    //selects last element as pivot, pi using which array is partitioned. 
    int partition(int intArray[], int low, int high) { 
        int pi = intArray[high];  
        int i = (low-1); // smaller element index   
        for (int j=low; j<high; j++) { 
            // check if current element is less than or equal to pi 
            if (intArray[j] <= pi) { 
                i++; 
                // swap intArray[i] and intArray[j] 
                int temp = intArray[i]; 
                intArray[i] = intArray[j]; 
                intArray[j] = temp; 
            } 
        } 
   
        // swap intArray[i+1] and intArray[high] (or pi) 
        int temp = intArray[i+1]; 
        intArray[i+1] = intArray[high]; 
        intArray[high] = temp; 
   
        return i+1; 
    } 
   
   
  //routine to sort the array partitions recursively
    void quick_sort(int intArray[], int low, int high) { 
        if (low < high) { 
            //partition the array around pi=>partitioning index and return pi
            int pi = partition(intArray, low, high); 
   
            // sort each partition recursively 
            quick_sort(intArray, low, pi-1); 
            quick_sort(intArray, pi+1, high); 
        } 
    } 
}
 
class Main{
    public static void main(String args[]) {
        //initialize a numeric array, intArray
        int intArray[] = {4,-1,6,8,0,5,-3}; 
        int n = intArray.length; 
        //print the original array
        System.out.println("Original Array: " + Arrays.toString(intArray));
        //call quick_sort routine using QuickSort object
        QuickSort obj = new QuickSort(); 
        obj.quick_sort(intArray, 0, n-1); 
        //print the sorted array
        System.out.println("\nSorted Array: " + Arrays.toString(intArray)); 
    } 
}