Java Exercises: Bead Sort Algorithm

Java Sorting Algorithm: Exercise-8 with Solution

Write a Java program to sort an array of positive integers using the Bead Sort Algorithm.

According to Wikipedia "Bead sort, also called gravity sort, is a natural sorting algorithm, developed by Joshua J. Arulanandham, Cristian S. Calude and Michael J. Dinneen in 2002, and published in The Bulletin of the European Association for Theoretical Computer Science. Both digital and analog hardware implementations of bead sort can achieve a sorting time of O(n); however, the implementation of this algorithm tends to be significantly slower in software and can only be used to sort lists of positive integers. Also, it would seem that even in the best case, the algorithm requires O(n2) space".

Sample Solution:

Java Code:

public class BeadSort 
{
	public static void main(String[] args)
	{
		BeadSort now=new BeadSort();
		int[] arr=new int[(int)(Math.random()*11)+5];
		for(int i=0;i<arr.length;i++)
			arr[i]=(int)(Math.random()*10);
		System.out.print("Unsorted: ");
		now.display1D(arr);
 
		int[] sort=now.beadSort(arr);
		System.out.print("Sorted: ");
		now.display1D(sort);
	}
	int[] beadSort(int[] arr)
	{
		int max=0;
		for(int i=0;i<arr.length;i++)
			if(arr[i]>max)
				max=arr[i];
 
		//Set up abacus
		char[][] grid=new char[arr.length][max];
		int[] levelcount=new int[max];
		for(int i=0;i<max;i++)
		{
			levelcount[i]=0;
			for(int j=0;j<arr.length;j++)
				grid[j][i]='_';
		}
		/*
		display1D(arr);
		display1D(levelcount);
		display2D(grid);
		*/
 
		//Drop the beads
	
		for(int i=0;i<arr.length;i++)
		{
			int num=arr[i];
			for(int j=0;num>0;j++)
			{
				grid[levelcount[j]++][j]='*';
				num--;
			}
			
		}
		
		System.out.println();
		display2D(grid);
		//Count the beads
		int[] sorted=new int[arr.length];
		for(int i=0;i<arr.length;i++)
		{
			int putt=0;
			for(int j=0;j<max&&grid[arr.length-1-i][j]=='*';j++)
				putt++;
			sorted[i]=putt;
		}
 
		return sorted;
	}
	void display1D(int[] arr)
	{
		for(int i=0;i<arr.length;i++)
			System.out.print(arr[i]+" ");
		System.out.println();
	}
	void display1D(char[] arr)
	{
		for(int i=0;i<arr.length;i++)
			System.out.print(arr[i]+" ");
		System.out.println();
	}
	void display2D(char[][] arr)
	{
		for(int i=0;i<arr.length;i++)
			display1D(arr[i]);
		System.out.println();
	}
}

Sample Output:

Unsorted: 8 2 2 3 4 6 7 8 4 0 8 

* * * * * * * * 
* * * * * * * * 
* * * * * * * * 
* * * * * * * _ 
* * * * * * _ _ 
* * * * _ _ _ _ 
* * * * _ _ _ _ 
* * * _ _ _ _ _ 
* * _ _ _ _ _ _ 
* * _ _ _ _ _ _ 
_ _ _ _ _ _ _ _ 

Sorted: 0 2 2 3 4 4 6 7 8 8 8 

Flowchart:

Java Code Editor:

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