programming-examples/java/Graph_Problems_Algorithms/Java Program to Implement Rope.java

/*This is a Java Program to implement Rope. A rope is a data structure for storing and manipulating a very long string.*/

/**
 * Java Program to Implement Rope
 **/

import java.util.Scanner;

/** Class RopeNode **/
class RopeNode
{
    RopeNode left, right;
    String data;
    int weight;
    /** Constructor **/
    public RopeNode(String data)
    {
        this.data = data;
        left = null;
        right = null;
        weight = data.length();
    }
    /** Constructor **/
    public RopeNode()
    {
        data = null;
        left = null;
        right = null;
        weight = 0;
    }
}

/** Class Rope **/
class Rope
{
    RopeNode root;

    /** Constructor **/
    public Rope()
    {
        root = new RopeNode("");
    }
    /** Function to clear rope **/
    public void makeEmpty()
    {
        root = new RopeNode("");
    }
    /** Function to concat an element **/
    public void concat(String str)
    {
        RopeNode nptr = new RopeNode(str);
        RopeNode newRoot = new RopeNode();
        newRoot.left = root;
        newRoot.right = nptr;
        newRoot.weight = newRoot.left.weight ;
        if (newRoot.left.right != null)
            newRoot.weight += newRoot.left.right.weight;
        root = newRoot;
    }
    /** Function get character at a paricular index **/
    public char indexAt(int ind)
    {
        RopeNode tmp = root;
        if (ind > tmp.weight)
            {
                ind -= tmp.weight;
                return tmp.right.data.charAt(ind);
            }
        while (ind < tmp.weight)
            tmp = tmp.left;
        ind -= tmp.weight;
        return tmp.right.data.charAt(ind);
    }
    /** Function get substring between two indices **/
    public String substring(int start, int end)
    {
        String str = "";
        boolean found = false;
        RopeNode tmp = root;
        if (end > tmp.weight)
            {
                found = true;
                end -= tmp.weight;
                if (start > tmp.weight)
                    {
                        start -= tmp.weight;
                        str = tmp.right.data.substring(start, end);
                        return str;
                    }
                else
                    str = tmp.right.data.substring(0, end);
            }
        if (!found)
            {
                while (end <= tmp.weight)
                    tmp = tmp.left;
                end -= tmp.weight;
                if (start >= tmp.weight)
                    {
                        start -= tmp.weight;
                        str = tmp.right.data.substring(start, end) + str;
                        return str;
                    }
                str = tmp.right.data.substring(0, end);
            }
        tmp = tmp.left;
        while (start < tmp.weight)
            {
                str = tmp.right.data + str;
                tmp = tmp.left;
            }
        start -= tmp.weight;
        str = tmp.right.data.substring(start) + str;
        return str;
    }
    /** Function to print Rope **/
    public void print()
    {
        print(root);
        System.out.println();
    }
    private void print(RopeNode r)
    {
        if (r != null)
            {
                print(r.left);
                if (r.data != null)
                    System.out.print(r.data);
                print(r.right);
            }
    }
}

/** Class RopeTest **/
public class RopeTest
{
    public static void main(String[] args)
    {
        Scanner scan = new Scanner(System.in);
        /** Creating object of Rope **/
        Rope r = new Rope();
        System.out.println("Rope Test\n");
        char ch;
        /**  Perform rope operations  **/
        do
            {
                System.out.println("\nRope Operations\n");
                System.out.println("1. concat ");
                System.out.println("2. get character at index");
                System.out.println("3. substring");
                System.out.println("4. clear");
                int choice = scan.nextInt();
                switch (choice)
                    {
                    case 1 :
                        System.out.println("Enter string to concat");
                        r.concat( scan.next() );
                        break;
                    case 2 :
                        System.out.println("Enter index");
                        System.out.println("Character at index = "+ r.indexAt(scan.nextInt()));
                        break;
                    case 3 :
                        System.out.println("Enter integer start and end limit");
                        System.out.println("Substring : "+ r.substring( scan.nextInt(), scan.nextInt() ));
                        break;
                    case 4 :
                        System.out.println("\nRope Cleared\n");
                        r.makeEmpty();
                        break;
                    default :
                        System.out.println("Wrong Entry \n ");
                        break;
                    }
                /**  Display rope  **/
                System.out.print("\nRope : ");
                r.print();
                System.out.println("\nDo you want to continue (Type y or n) \n");
                ch = scan.next().charAt(0);
            }
        while (ch == 'Y'|| ch == 'y');
    }
}

/*
Rope Operations

1. concat
2. get character at index
3. substring
4. clear
1
Enter string to concat
rope

Rope : rope

Do you want to continue (Type y or n)

y

Rope Operations

1. concat
2. get character at index
3. substring
4. clear
1
Enter string to concat
is

Rope : ropeis

Do you want to continue (Type y or n)

y

Rope Operations

1. concat
2. get character at index
3. substring
4. clear
1
Enter string to concat
a

Rope : ropeisa

Do you want to continue (Type y or n)

y

Rope Operations

1. concat
2. get character at index
3. substring
4. clear
1
Enter string to concat
datastructure

Rope : ropeisadatastructure

Do you want to continue (Type y or n)

y

Rope Operations

1. concat
2. get character at index
3. substring
4. clear
2
Enter index
5
Character at index = s

Rope : ropeisadatastructure

Do you want to continue (Type y or n)

y

Rope Operations

1. concat
2. get character at index
3. substring
4. clear
2
Enter index
13
Character at index = r

Rope : ropeisadatastructure

Do you want to continue (Type y or n)

y

Rope Operations

1. concat
2. get character at index
3. substring
4. clear
3
Enter integer start and end limit
5 15
Substring : sadatastru

Rope : ropeisadatastructure

Do you want to continue (Type y or n)

y

Rope Operations

1. concat
2. get character at index
3. substring
4. clear
4

Rope Cleared


Rope :

Do you want to continue (Type y or n)

n