Radix Sort in Java

Author: Deepali-Srivastava

sorting/radix-sort/Node.java

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+/*
+Copyright (C) Deepali Srivastava - All Rights Reserved
+This code is part of DSA course available on CourseGalaxy.com    
+*/
+
+
+public class Node 
+{
+     public int info;  
+     public Node link;
+    
+     public Node(int i) 
+	 {
+		info=i;
+		link=null;
+	 }
+}
+
+

sorting/radix-sort/RadixSort.java

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+/*
+Copyright (C) Deepali Srivastava - All Rights Reserved
+This code is part of DSA course available on CourseGalaxy.com    
+*/
+
+import java.util.Scanner;
+
+public class RadixSort 
+{
+	public static Node sort(Node start)
+	{
+		Node[] rear = new Node[10];
+		Node[] front = new Node[10];
+
+		int leastSigPos=1;
+		int mostSigPos=digitsInLargest(start);
+
+		int i,dig;
+		Node p;
+		for(int k=leastSigPos; k<=mostSigPos; k++) 
+		{
+			/*Making all the queues empty at the beginning of each pass*/
+			for(i=0; i<=9 ; i++)
+			{
+				rear[i] = null;
+				front[i] = null;
+			}
+						
+			for(p=start; p!=null; p=p.link)
+			{
+				/*Find kth digit from right in the number*/
+				dig = digit(p.info,k);
+			
+				/*Insert the node in Queue(dig) */
+				if(front[dig] == null)			
+					front[dig]=p;
+				else
+					rear[dig].link=p;
+				rear[dig]=p;
+			}
+			
+			/*Join all queues to form new linked list*/
+			i=0;
+			while(front[i] == null)  /*Finding first non empty queue*/
+				i++;
+			start = front[i]; 	
+			while(i<=8) 
+			{
+				if(rear[i+1]!=null) /*if (i+1)th  queue is not empty*/
+					rear[i].link=front[i+1]; /*join end of ith queue to start of (i+1)th queue*/
+				else							
+					rear[i+1]=rear[i]; /*continue with rear[i]*/
+				i++;
+			}
+			rear[9].link=null;  
+		}
+		return start;
+	}/*End of sort*/
+
+	/*Returns number of digits in the largest element of the list */
+	public static int digitsInLargest(Node start)  
+	{
+		/*Find largest element*/
+		int large=0;
+		Node p=start;
+		while(p!=null)
+		{
+			if(p.info > large)
+				large = p.info;
+			p=p.link;
+		}
+		
+		/*Find number of digits in largest element*/
+		int ndigits=0;
+		while(large!=0)
+		{
+			ndigits++;
+			large/=10;
+		}
+		return ndigits;
+	} 
+
+	/*Returns kth digit from right in n*/
+	public static int digit(int n, int k)
+	{
+		int d=0,i;
+		for(i=1; i<=k; i++)
+		{
+			d=n%10;
+			n/=10;
+		}
+		return d;
+	}
+
+	public static void main(String[] args) 
+	{		
+		Node temp,p;
+		int i,n,data;
+
+		Scanner scan = new Scanner(System.in);	
+				
+		System.out.println("Enter number of elements in the list : ");
+		n = scan.nextInt();
+    	
+		Node start=null;
+		for(i=1; i<=n; i++)  /*Inserting elements in linked list*/
+		{
+			System.out.print("Enter element " + i + " ");
+			data = scan.nextInt();
+		
+			temp = new Node(data);
+			if(start==null)
+				start=temp;
+			else
+			{
+				p=start;
+				while(p.link!=null)
+					p=p.link;
+				p.link=temp;
+			}
+		}
+		
+		start = sort(start);
+		
+		System.out.println("Sorted list is :\n");
+		p=start;
+		while(p!=null)
+		{
+			System.out.print(p.info + " ");
+			p=p.link;
+		}
+		System.out.println();
+		scan.close();
+	}
+}