Finding the maximum node in a Binary Tree - Two methods ( Java )

 Finding the maximum node in a Binary Tree - Two methods ( Java )

Input

10 20 30 40 50 60 70

Output

70

Method 1 :

Using Queue and List 

Traversing all the nodes of the tree using the queue and storing all the values of the node in the list and returning the maximum value in the List.

Code

import java.util.*;
class Nod{
	int data;
	Nod left,right;
	Nod(int k)
	{
		data=k;
	}
}
public class MaxNode {
	public static int getMax(Nod root)
	{
		if(root==null)
			return -1;
	    Queue <Nod> q=new LinkedList<Nod>();
	    List<Integer> arr=new ArrayList<Integer>();
	    q.add(root);
		arr.add(root.data);
		while(q.isEmpty()==false)
		{
			Nod curr=q.poll();
			arr.add(curr.data);
			if(curr.left!=null)
				q.add(curr.left);
			if(curr.right!=null)
				q.add(curr.right);
		}
		return Collections.max(arr);
	}
	
	public static void main(String[] args) {
		Nod root=new Nod(10);        //     10
		root.left=new Nod(20);      //   20     30
		root.right=new Nod(30);    //  40  50  60  70
		root.left.left=new Nod(40);
		root.left.right=new Nod(50);
		root.right.left=new Nod(60);
		root.right.right=new Nod(70);
		System.out.println(getMax(root));
	}

}

Method 2 ( Efficient )

Using simple recursion 

Simply comparing the current root data with the maximum node values of the subtree (i.e left subtree and right subtree) using recursion.

Code

import java.util.*;
class Nod{
	int data;
	Nod left,right;
	Nod(int k)
	{
		data=k;
	}
}
public class MaxNode {
	//Efficient Method
	public static int getMax(Nod root)
	{
		if(root==null)
			return Integer.MIN_VALUE;
		return Math.max(root.data, Math.max(getMax(root.left), getMax(root.right)));
	}
	public static void main(String[] args) {
		Nod root=new Nod(10);        //     10
		root.left=new Nod(20);      //   20     30
		root.right=new Nod(30);    //  40  50  60  70
		root.left.left=new Nod(40);
		root.left.right=new Nod(50);
		root.right.left=new Nod(60);
		root.right.right=new Nod(70);
		System.out.println(getMax(root));
	}

}

Output :

Input
10 20 30 40 50 60 70

Output
70

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