Find maximum element in binary tree in java

If you want to practice data structure and algorithm programs, you can go through data structure and algorithm interview questions.
This is 11th part of java binary tree tutorial.

In this post, we will see about program to find maximum element  in a binary tree in java.

There can be two solutions for it.
  • Recursive
  • Iterative

Recursive solution:

Algorithm :

Steps for getting maximum element in binary tree:
  • Find maximum element in left subtree
  • Find maximum element in right subtree
  • Compare maximum of above subtrees to current node
  • We will find maximum element with above steps

Code for recursion will be:

        // Recursive Solution
 /* To get max node in a binary tree*/
 public static  int getMaximumRec(TreeNode root)
 {
  int max=Integer.MIN_VALUE;
  int value=0;
  int left,right;
  if(root != null)  
  {
   value=root.data;
   left=getMaximumRec(root.left);
   right=getMaximumRec(root.right);

   if(left>right)
   {
    max=left;
   }
   else
   {
    max=right;
   }

   if(max < value)
   {
    max=value;
   }
  }

  return max;
 }

Iterative solution:

Iterative solution will be similar to level order traversal. When we are popping element from queue, we will check max.

Code for iteration will be :

 
        // Iterative Solution
 /* To get max node in a binary tree*/
 public static int getMaximumItr(TreeNode startNode) {

  Queue<TreeNode> queue=new LinkedList<TreeNode>();
  queue.add(startNode);
  int max=Integer.MIN_VALUE;
  while(!queue.isEmpty())
  {
   TreeNode tempNode=queue.poll();
   if(max < tempNode.data)
    max=tempNode.data;
   if(tempNode.left!=null)
    queue.add(tempNode.left);
   if(tempNode.right!=null)
    queue.add(tempNode.right);
  }
  return max;
 }


Lets create java program to get maximum element in binary tree:

Lets say, your binary tree is this:
package org.arpit.java2blog;

import java.util.LinkedList;
import java.util.Queue;

public class BinaryTree {
    /*
     * @Author : Arpit Mandliya
     */

 public static class TreeNode
 {
  int data;
  TreeNode left;
  TreeNode right;
  TreeNode(int data)
  {
   this.data=data;
  }
 }

 // Recursive Solution
 /* To get max node in a binary tree*/
 public static  int getMaximumRec(TreeNode root)
 {
  int max=Integer.MIN_VALUE;
  int value=0;
  int left,right;
  if(root != null)  
  {
   value=root.data;
   left=getMaximumRec(root.left);
   right=getMaximumRec(root.right);

   if(left>right)
   {
    max=left;
   }
   else
   {
    max=right;
   }

   if(max < value)
   {
    max=value;
   }
  }

  return max;
 }

 // Iterative Solution
 /* To get max node in a binary tree*/
 public static int getMaximumItr(TreeNode startNode) {

  Queue<TreeNode> queue=new LinkedList<TreeNode>();
  queue.add(startNode);
  int max=Integer.MIN_VALUE;
  while(!queue.isEmpty())
  {
   TreeNode tempNode=queue.poll();
   if(max < tempNode.data)
    max=tempNode.data;
   if(tempNode.left!=null)
    queue.add(tempNode.left);
   if(tempNode.right!=null)
    queue.add(tempNode.right);
  }
  return max;
 }


 public static void main(String[] args)
 {
  BinaryTree bi=new BinaryTree();
  // Creating a binary tree
  TreeNode rootNode=createBinaryTree();
  System.out.println("Max node using recursion :"+getMaximumRec(rootNode));
  System.out.println("Max node using iteration :"+getMaximumItr(rootNode));
 }

 public static TreeNode createBinaryTree()
 {

  TreeNode rootNode =new TreeNode(40);
  TreeNode node20=new TreeNode(20);
  TreeNode node10=new TreeNode(10);
  TreeNode node30=new TreeNode(30);
  TreeNode node60=new TreeNode(60);
  TreeNode node50=new TreeNode(50);
  TreeNode node70=new TreeNode(70);

  rootNode.left=node20;
  rootNode.right=node60;

  node20.left=node10;
  node20.right=node30;

  node60.left=node50;
  node60.right=node70;

  return rootNode;
 }
}


Run above program and you will get following output:
 
Max node using recursion :70
Max node using iteration :70

Java Binary tree tutorial:

    Binary tree in java Binary tree preorder traversal Binary tree postorder traversal Binary tree inorder traversal Binary tree level order traversal Binary tree spiral order traversal Binary tree reverse level order traversal Binary tree boundary traversal Print leaf nodes of binary tree Count leaf nodes in binary tree get maximum element in binary tree Print all paths from root to leaf in binary tree Print vertical sum of binary tree in java Get level of node in binary tree in java Lowest common ancestor(LCA) in binary tree in java

Please go through java interview programs for more such programs.

Written by Arpit:

If you have read the post and liked it. Please connect with me on Facebook | Twitter | Google Plus

 

Java tutorial for beginners Copyright © 2012