Java Program for Quick Sorting

What is quick sort ?

Quick sort is one of the divide-and-conquer algorithm.

Quick sort is to sort an array array[0], array[1],....array[n] by picking some element in the array as pivot element around which to rearrange the elements in the array in order to get sorted elements.

Quick sort reduces the space complexity and removes the use of the auxiliary array that is used in merge sort.

Use random pivot instead of first array element as pivot element to reduces the time complexity.

Quick Sort Algorithm

Pick the pivot element in random which can be first element also in the array.

Move all the elements in left side of pivot element which are less than pivot element.

Move all the elements in right side of pivot element which are greater than pivot element.

Partition array elements which are less than pivot element and repeat the process 1 to 3 till all sub array elements in sorted order.

Partition array elements which are greater than or equal to pivot element and repeat the process 1 to 3 till all sub array elements in sorted order.

Quick Sorting Steps

quick sorting

Quick Sorting Time complexity

Quick sorting time complexity is O(NlogN), here N is the number of elements in the list. worst case time complexity of this algorithm is O(N^2).

Quick Sorting Java Program

import java.util.Scanner;

public class QuickSortingTest {
	public static void swap(int[] listVals, int index1, int index2){
		int temp = listVals[index1];
		listVals[index1] = listVals[index2];
		listVals[index2] = temp;
	}    
	
	public static int partitionByPivot(int[] listVals, int startIndex, int endIndex){
		int i = startIndex + 1;
		// First element as pivot element.
		int pivotElement = listVals[startIndex];
		for(int j=startIndex+1;j<endIndex+1;j++){
	        // Arranges the list elements which are less than pivot                  
	        // on one side and which are greater that on other side.
			if(listVals[j]<pivotElement){
				swap(listVals, i, j);
				i += 1;
			}
		}
		// swaps pivot element in correct position
		swap(listVals, startIndex, i-1);
		// returns the updated pivot element position
		return i-1;
	}
	
	public static void quickSort(int[] listVals, int startIndex, int endIndex){
		if(startIndex < endIndex){
			// position of pivot element
			int pivotElementPosition =  partitionByPivot(listVals, startIndex, endIndex);
			quickSort(listVals, startIndex, pivotElementPosition-1);
			quickSort(listVals, pivotElementPosition+1, endIndex);
		}
	}

	public static void main(String[] args){
	    int[] numberList;
	    Scanner in = new Scanner(System.in); 
	    System.out.println("Quick Sorting");
	    System.out.println("--------------------");
	    System.out.println("Enter numbers count: ");                   
	    int count = in.nextInt();                   
	    numberList = new int[count];
	    System.out.println("Enter numbers: "); 
	    for (int i=0;i<count;i++){
	    	numberList[i]=in.nextInt();
	    }
	    in.close();
	    quickSort(numberList, 0, numberList.length-1);
	    
	    System.out.println("Sorted numbers: "); 
	    for(int number : numberList){
	    	System.out.print(number+"\t");
	    }
	}
}                                                                                                                                                                                                                
Output:
$ javac QuickSortingTest.java
$ java QuickSortingTest 
Quick Sorting
--------------------
Enter numbers count: 
5
Enter numbers: 
24
18
32
15
7
Sorted numbers: 
7	15	18	24	32	


Java Examples

GCD and Rational Number Java Program

Java Queue Program using exception

Java Stack Program using exception

Addition of three integers java program

Biggest of three integers java program

Fibonacci numbers java program

Arithmetic Operations Menu java program

Second Smallest Element In Array Java Program

Transpose Of A Matrix Java Program

Java Program to Display triangle of stars (*)

Java Programming Prints Product Tables

Java Program to Display triangle of numbers

Java Program to Get Current Date

Java Program to Find Character Vowel or Consonent

Java Program to Compute HCF and LCM

Java Program to Sum the Command Line Integer Arguments

Java Programm to Multiply the Command Line Integer Arguments

Java Program to Find Multiplication of Command Line Floating Point Numeric Arguments

Java Program to Check String Contains or Not

Java Program to Get Grade Description using Switch

Java Program for CSV File Reader

Java Program to Find Character Frequency Count in String using for each

Java Program to Find Min from Integer Array by Passing Array to Method

Java Program Linear Search

Binary Search Java Program

Ternary Search Java Program

Java Program to Generate Range of Numbers

Java Program to Generate Range of Characters

Java Program to Compute Square Root Value

Java Program to Check Number is Positive or Negative

Java Program to Check Number is Odd or Even

Java Program to Compute Plot Area

Java Program to Convert Number of Days into Years

Java Program to Check a Year is Leap Year, Century Year or Not

Java Program to Check a Character is Digit, Letter or neither digit nor letter

Java Program to Check a Number is Palindrome or not

Java Program to Sum Two Matrix

Java Program to Compute Power

Java Program to Check Number is an Armstrong Number or not

Java Program for Temperature Unit Conversions

Java Program to Generate Random Numbers in Specified Range

Java Program to Compute Sum of Digits and Product of Digits

Java Program to Compute Reverse Number

Java Programming Computes Factorial Value

Java Programming Checks Prime Number or not

Java Program to Compute Harmonic Series

Java Program Generate Floyd's Triangle

Java Program to Reverse String

Java Program to Check Palindrome String or not

Java Program to Open Notepad

Java Program to Search String using RegEx Pattern

Java Program to Search Word in String

Java Program to Get System Environment Variables

Java Program to Get IP Address of Server Name

Java Program for Arrays Sorting and Reverse using sort method

Java Program for Bubble Sorting

Java Program for Selection Sorting

Java Program for Insertion Sorting

Java Program for Merge Sorting

Java Program for Quick Sorting

Java Program for Counting Sort

Java Program for Radix Sorting

Java Program for Sorting Array of Strings

Java Program for String Characters Sorting

Java Program to Sum First N Numbers

Java Program to Product First N Numbers

Java Program to get URL details

Java Program to get URL HTML Content

Java Program to get URL details

Java Program to get URL HTML Content

Privacy Policy  |  Copyrightcopyright symbol2020 - All Rights Reserved.  |  Contact us   |  Report website issues in Github   |  Facebook page   |  Google+ page

Email Facebook Google LinkedIn Twitter
^