Question

Hierarchical structures:

Write a java class to implement a Multi-way tree, with an appropriate constructor and methods for the following:

            Methods to find and insert on the tree.

            Method to return the height of the tree.

Methods to output the values from this tree in any one of the following ways:

            Pre-order:        Left to right order of siblings

            Post-order:      Right to left order of siblings

            Level order:    Left to right order of siblings

            Method to store the tree to a file per the format used for reading the file.

Write a Java application that reads an input file that describes a flattened tree and constructs the corresponding tree. The format of the is as follows:

The first line has an integer value, m, for an m-way tree described in the file.

The second line indicates the value at the root.

Each subsequent line will describe a node in the tree. There will be up to m+1 integer values separated by a space. The first is the value at the node, and the subsequent values indicate the values in its children nodes.

Example:

3                                  The file describes a 3-way tree

1                                  The root has value 1

1 8 22 29                     Node with value 1 has children with values 8, 22, and 29

8 3 5 17

3 16 19 32

22 42                           Node with value 22 has a child with value 42.

19 10 15

42 13 18 49 55

29 4 9

Your implementation should handle a value of m read from the file. There will be any number of input lines.  A value will be described as a child before it is described with children i.e. parent node will be described before its children. Use recursion and arrays. Note that the tree is not a search-tree.

Answer 1

//java program to print a multi way tree

package com;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;

class MultiWayTree<T extends Comparable<T>> {
   // left subtree
   MultiWayTree<T> left;
   //right subtree
   MultiWayTree<T> right;
   //elements of tree
   T data;
   //Constructor
   public MultiWayTree(T data) {
   this.data = data;
   this.left = null;
   this.right = null;
   }

   public void insert(T value) {
   //value <= data
   if(value.compareTo(data) <= 0) {
   if(left == null) {
   // Insert at empty tree
   left = new MultiWayTree<T>(value);
   }
   else {
  
   left.insert(value);
   }
   }
   else { // value > data
   if(right == null) {
   // Insert at empty tree
   right = new MultiWayTree<T>(value);
   }
   else {
     
   right.insert(value);
   }
   }
      
   }
   public boolean find(T value) {
   if(value.compareTo(data) == 0) {
   // Value found
   return true;
   }
   else if(value.compareTo(data) < 0) {
   return (left == null)
   ? false //there are no more MultiWayTrees in left subtree to check
   : left.find(value); // Continue searching left subtree
   }
   else { // data.compareTo(value) > 0
   return (right == null)
   ? false // Not found; there are no more MultiWayTrees in right subrtree to check
   : right.find(value); // Continue searching right subtree
   }
   }

   //preOrder of tree
   public void preOrder() {
   if(left != null) {
   left.preOrder();
   }
   System.out.print(data + " ");
     
   }
   //method for postOrder
   public void postOrder() {
   System.out.print(data + " ");

   if(right != null) {
   right.postOrder();
   }
   }

   public static void main(String[] args) throws IOException {
       List<String> filedata = new ArrayList<String>();
         
       //read tree from a text file
   try
   {
   FileInputStream in = new FileInputStream("input.txt");
   BufferedReader br = new BufferedReader(new InputStreamReader(in));
   String line;
     
   while((line = br.readLine())!= null)
   {
       MultiWayTree<String> root = new MultiWayTree<String>( line);
   filedata.add(line);
  
   }
   br.close();
   }catch(Exception e)
   {
   System.out.println(e);
   }
   System.out.println(filedata);
   //write tree to a text file
   FileWriter fw=new FileWriter(new File("output.txt"));
   for(String f:filedata)
   {
   fw.write(f);
   }
   fw.close();   
   }
   }

//input.txt

3
1
1 8 22 29
8 3 5 17
3 16 19 32
22 42   
19 10 15
42 13 18 49 55
29 4 9

output.txt created