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Thread: Radix Sort

  1. #1
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    Default Radix Sort

    Hello guys, I am implementing a Radix Sort using an array of queues.
    So far I have created the array and print it and is working fine.
    I have also extracted the LSD from each integer.
    No my target is to store the integers it the queues according to the LSD. (This would be the first pass).
    This is supposed to be processed in the for looped between line 29 and 35.
    -- problem is that when I deque the integers are being displayed in the same way as at the beginning!
    I know my problem is in my enqueue but I don't know how to do it.
    Here is the code:-
    import java.util.*;
     
    public class MainProgram
    {
     
        public static void main(String[] args)
        {
     
    	Scanner userinput = new Scanner(System.in);
    	System.out.print("Please enter the size of the array. ");
    	int count = userinput.nextInt(); //user enters the size of the array.
     
    	int[] numbers = new int[count];  //array containing hte integers.
    	int r=0;
     
       	QueueLinkedList[] queue = new QueueLinkedList[10]; //created an instance of the queue. 10 bins needed for the Radix Sort.
    	for(int i=0; i<queue.length; i++)
    		{
              	queue[i] = new QueueLinkedList();
            }
     
    	for(int index = 0; index < numbers.length; index++) //generating random integers.
    		{
    			numbers[index] = (int)(Math.random()*1001);
    			System.out.print(index+"    ");
    			System.out.println(numbers[index]);
    		}	
     
    		for(int i=0; i<numbers.length; i++) //identifying the LSD and store the integers in queues accoring to the LSD.
    		{									//the mistake is in this loop!				
    			numbers[r] = (numbers[i] % 10)/1;
    		//	System.out.println(numbers[r]);
    		    queue[r].enqueue(numbers[i]);
    		    //queue[r].dequeue();
     
    		}
    		for(int i=0;i<queue.length;i++){  //deque and printing the integers. Here the integers should be sorted by the LSD. 1st PASS.
    			queue[r].dequeue();				//however output is noot good!
    		}
        }    
    }
    Thanks in advance for your help.


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Radix Sort

    The posted code does not compile because of missing class.

    Also at http://forums.devshed.com/java-help-...ml#post2841315
    If you don't understand my answer, don't ignore it, ask a question.

  3. #3
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    Default Re: Radix Sort

    What class? If you are refering to the QueueLinkedList... I have a class for that which is working fine as a queue. Tks.

  4. #4
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    Default Re: Radix Sort

    There is no way to test the code since it does not compile.
    If you don't understand my answer, don't ignore it, ask a question.

  5. #5
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    Default Re: Radix Sort

    Ok so shall I post also the other class so it can be compiled?

  6. #6
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    Default Re: Radix Sort

    If you are looking for others to test your code they'll need all the class definitions.
    If you don't understand my answer, don't ignore it, ask a question.

  7. #7
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    Default Re: Radix Sort

    Ok so here is my code.
    import java.util.*;
     
    public class MainProgram
    {
     
        public static void main(String[] args)
        {
     
    	Scanner userinput = new Scanner(System.in);
    	System.out.print("Please enter the size of the array. ");
    	int count = userinput.nextInt(); //user enters the size of the array.
     
    	int[] numbers = new int[count];  //array containing hte integers.
    	int r=0;
     
       	QueueLinkedList[] queue = new QueueLinkedList[10]; //created an instance of the queue. 10 bins needed for the Radix Sort.
    	for(int i=0; i<queue.length; i++)
    		{
              	queue[i] = new QueueLinkedList();
            }
     
    	for(int index = 0; index < numbers.length; index++) //generating random integers.
    		{
    			numbers[index] = (int)(Math.random()*1001);
    			System.out.print(index+"    ");
    			System.out.println(numbers[index]);
    		}	
     
    		for(int i=0; i<numbers.length; i++) //identifying the LSD and store the integers in queues accoring to the LSD.
    		{									//the mistake is in this loop! In the enqueue I believe.				
    			numbers[i] = (numbers[i] % 10)/1;
    		//	System.out.println(numbers[r]);
    		    queue[i].enqueue(numbers[i]);
    		    //queue[r].dequeue();
     
    		}
    		for(int i=0;i<queue.length;i++){  //deque and printing the integers. Here the integers should be sorted by the LSD. 1st PASS.
    			queue[i].dequeue();				//however output is noot good!
    		}
        }    
    }
    class QueueLinkedList {
        private Node head;
     
        //LinkedList constructor
        public QueueLinkedList()
        	{
    	    	head = null;
        	}
     
        //Inserts a new Link at the head of the list                
        public void enqueue(int d1)
        	{
    	    	Node node = new Node(d1);
    			Node temp = head;
     
    			if (head == null)
    				{
    					head = node;
    				}
    		  	else
    				{
    					while (temp.nextNode != null)
    		    		temp = temp.nextNode;
     
    	  	  			temp.nextNode = node;
      				}	   
        	}
     
             public Node dequeue() 
             	{  
             		Node temp = null;
              		if(head==null)  
                    	{  
                        	  System.out.println("Queue is empty!");
                    	}  
                	else  
                    	{  
                    		  temp = head;  
                       	 	  head = head.nextNode;  
                              temp.printList();    
                    	}  
                    return temp;
                }    
     
        //Prints list data
        public void printList()
        	{
    	    	Node temp = head;
    	    System.out.println("List: ");
    	    while(temp != null)
    	    	{
    		    	temp.printList();
    		    temp = temp.nextNode;
     
    	    }
    	    System.out.println("");
     
        }
        	 public void printLastItem()
    	 {
    	 	Node temp = head;
    	 	while(temp.nextNode !=null)
    	 		{
    	 			temp = temp.nextNode;
    	 		}
    	 		temp.printList();
     
    	 }
    	 	public void peek()
    	 	{
    	 		Node temp = head;
    	 		temp.printList();
    	 	}
     
     
    	 	public void isEmpty()
    	 	{
    	 		if(head == null)
    	 			{
    	 				System.out.println("Queue is empty!");
    	 			}
    	 		else
    	 			{
    	 				System.out.println("Queue is not empty!");
    	 			}
    	 	}
     
    	 	public void length()
    	 	{
    	 	Node temp = head;
    	    int count = 0;
    	    while(temp != null)
    	    	{
     
    		    temp = temp.nextNode;
    		    count = count + 1;
     
    	 	}
    	 	System.out.println(count);
    	 	}
     
     
    }
    class Node{
        public int data1;
        public Node nextNode;
     
        //Link constructor
        public Node(int d1)
        	{
    	    	data1 = d1;
       		}
     
        //Print Link data
        public void printList() {
    	    System.out.println(data1);
        }
    }
    Ok so here is my program. Im trying to implement a radix sort but Im stuck. Can anyone take a look at my code and tell my how to proceed please. Im having trouble enqueueing the integers according to their LSD.
    Thanks in advance for ypur help!

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