programming-examples/java/Data_Structures/Java Program to Implement Patricia Trie.java

/*This is a Java Program to Implement Patricia Trie. A radix tree (also patricia trie or radix trie or compact prefix tree) is a space-optimized trie data structure where each node with only one child is merged with its child.*/

/**
 ** Java Program to Implement Patricia Trie
 **/

import java.util.Scanner;

/** Class PatriciaNode **/
class PatriciaNode
{
    int bitNumber;
    int data;
    PatriciaNode leftChild, rightChild;
}

/* Class PatriciaTrie */
class PatriciaTrie
{
    private PatriciaNode root;
    private static final int MaxBits = 10;

    /** Constructor **/
    public PatriciaTrie()
    {
        root = null;
    }
    /** function to check if empty **/
    public boolean isEmpty()
    {
        return root == null;
    }
    /** function to clear **/
    public void makeEmpty()
    {
        root = null;
    }
    /** function to get ith bit of key k from left **/
    private boolean bit(int k, int i)
    {
        String binary = Integer.toString(k, 2);
        while (binary.length() != MaxBits)
            binary = "0" + binary;
        if (binary.charAt(i - 1) == '1')
            return true ;
        return false;
    }
    /** function to search for an element **/
    public boolean search(int k)
    {
        int numOfBits = (int) (Math.log(k)/Math.log(2)) + 1;
        if (numOfBits > MaxBits)
            {
                System.out.println("Error : Number too large");
                return false;
            }
        PatriciaNode searchNode = search(root, k);
        if (searchNode.data == k)
            return true;
        else
            return false;
    }
    /** function to search for an element **/
    private PatriciaNode search(PatriciaNode t, int k)
    {
        PatriciaNode currentNode, nextNode;
        if (t == null)
            {
                return null;
            }
        nextNode = t.leftChild;
        currentNode = t;
        while (nextNode.bitNumber > currentNode.bitNumber)
            {
                currentNode = nextNode;
                nextNode = (bit(k, nextNode.bitNumber)) ? nextNode.rightChild : nextNode.leftChild;
            }
        return nextNode;
    }
    /** function to insert and element **/
    public void insert(int ele)
    {
        int numOfBits = (int) (Math.log(ele)/Math.log(2)) + 1;
        if (numOfBits > MaxBits)
            {
                System.out.println("Error : Number too large");
                return;
            }
        root = insert(root, ele);
    }
    /** function to insert and element **/
    private PatriciaNode insert(PatriciaNode t, int ele)
    {
        PatriciaNode current, parent, lastNode, newNode;
        int i;
        if (t == null)
            {
                t = new PatriciaNode();
                t.bitNumber = 0;
                t.data = ele;
                t.leftChild = t;
                t.rightChild = null;
                return t;
            }
        lastNode = search(t, ele);
        if (ele == lastNode.data)
            {
                System.out.println("Error : key is already present\n");
                return t;
            }
        for (i = 1; bit(ele, i) == bit(lastNode.data, i); i++);
        current = t.leftChild;
        parent = t;
        while (current.bitNumber > parent.bitNumber && current.bitNumber < i)
            {
                parent = current;
                current = (bit(ele, current.bitNumber)) ? current.rightChild : current.leftChild;
            }
        newNode = new PatriciaNode();
        newNode.bitNumber = i;
        newNode.data = ele;
        newNode.leftChild = bit(ele, i) ? current : newNode;
        newNode.rightChild = bit(ele, i) ? newNode : current;
        if (current == parent.leftChild)
            parent.leftChild = newNode;
        else
            parent.rightChild = newNode;
        return t;
    }
}

/* Class PatriciaTrie Test */
public class PatriciaTrieTest
{
    public static void main(String[] args)
    {
        Scanner scan = new Scanner(System.in);
        /* Creating object of PatriciaTrie */
        PatriciaTrie pt = new PatriciaTrie();
        System.out.println("Patricia Trie Test\n");
        char ch;
        /*  Perform trie operations  */
        do
            {
                System.out.println("\nPatricia Trie Operations\n");
                System.out.println("1. insert ");
                System.out.println("2. search");
                System.out.println("3. check emepty");
                System.out.println("4. make emepty");
                int choice = scan.nextInt();
                switch (choice)
                    {
                    case 1 :
                        System.out.println("Enter key element to insert");
                        pt.insert( scan.nextInt() );
                        break;
                    case 2 :
                        System.out.println("Enter key element to search");
                        System.out.println("Search result : "+ pt.search( scan.nextInt() ));
                        break;
                    case 3 :
                        System.out.println("Empty Status : "+ pt.isEmpty() );
                        break;
                    case 4 :
                        System.out.println("Patricia Trie cleared");
                        pt.makeEmpty();
                        break;
                    default :
                        System.out.println("Wrong Entry \n ");
                        break;
                    }
                System.out.println("\nDo you want to continue (Type y or n) \n");
                ch = scan.next().charAt(0);
            }
        while (ch == 'Y'|| ch == 'y');
    }
}

/*

Patricia Trie Operations

1. insert
2. search
3. check emepty
4. make emepty
3
Empty Status : true

Do you want to continue (Type y or n)

y

Patricia Trie Operations

1. insert
2. search
3. check emepty
4. make emepty
1
Enter key element to insert
24

Do you want to continue (Type y or n)

y

Patricia Trie Operations

1. insert
2. search
3. check emepty
4. make emepty
1
Enter key element to insert
6

Do you want to continue (Type y or n)

y

Patricia Trie Operations

1. insert
2. search
3. check emepty
4. make emepty
1
Enter key element to insert
28

Do you want to continue (Type y or n)

y

Patricia Trie Operations

1. insert
2. search
3. check emepty
4. make emepty
1
Enter key element to insert
5

Do you want to continue (Type y or n)

y

Patricia Trie Operations

1. insert
2. search
3. check emepty
4. make emepty
1
Enter key element to insert
63

Do you want to continue (Type y or n)

y

Patricia Trie Operations

1. insert
2. search
3. check emepty
4. make emepty
1
Enter key element to insert
19

Do you want to continue (Type y or n)

y

Patricia Trie Operations

1. insert
2. search
3. check emepty
4. make emepty
1
Enter key element to insert
94

Do you want to continue (Type y or n)

y

Patricia Trie Operations

1. insert
2. search
3. check emepty
4. make emepty
1
Enter key element to insert
24
Error : key is already present


Do you want to continue (Type y or n)

y

Patricia Trie Operations

1. insert
2. search
3. check emepty
4. make emepty
2
Enter key element to search
24
Search result : true

Do you want to continue (Type y or n)

y

Patricia Trie Operations

1. insert
2. search
3. check emepty
4. make emepty
2
Enter key element to search
5
Search result : true

Do you want to continue (Type y or n)

y

Patricia Trie Operations

1. insert
2. search
3. check emepty
4. make emepty
2
Enter key element to search
6
Search result : true

Do you want to continue (Type y or n)

y

Patricia Trie Operations

1. insert
2. search
3. check emepty
4. make emepty
2
Enter key element to search
7
Search result : false

Do you want to continue (Type y or n)

y

Patricia Trie Operations

1. insert
2. search
3. check emepty
4. make emepty
2
Enter key element to search
19
Search result : true

Do you want to continue (Type y or n)

y

Patricia Trie Operations

1. insert
2. search
3. check emepty
4. make emepty
2
Enter key element to search
15
Search result : false

Do you want to continue (Type y or n)

y

Patricia Trie Operations

1. insert
2. search
3. check emepty
4. make emepty
2
Enter key element to search
94
Search result : true

Do you want to continue (Type y or n)

y

Patricia Trie Operations

1. insert
2. search
3. check emepty
4. make emepty
2
Enter key element to search
97
Search result : false

Do you want to continue (Type y or n)

y

Patricia Trie Operations

1. insert
2. search
3. check emepty
4. make emepty
2
Enter key element to search
32
Search result : false

Do you want to continue (Type y or n)

y

Patricia Trie Operations

1. insert
2. search
3. check emepty
4. make emepty
2
Enter key element to search
28
Search result : true

Do you want to continue (Type y or n)

y

Patricia Trie Operations

1. insert
2. search
3. check emepty
4. make emepty
4
Patricia Trie cleared

Do you want to continue (Type y or n)

n