Find the maximum element in a binary tree without recursion.

Question: Given the root pointer to a binary tree, find the maximum element present in it.

Input: Sample Tree (Pointer to node 1 is given)
Output: Maximum = 9

We discussed how to find the maximum element in a binary tree using recursion in this post.

• Find maximum element in a binary tree

That involved recursion. If recursion seems difficult to you, we can even solve this problem with the help of level order traversal of binary tree. The property of level order traversal is that it passes through each element of the binary tree. Utilizing this property we can keep a track of the maximum element encountered in complete traversal. Then simply return the element. Here is an implementation to find the maximum element without using recursion.

#include<stdio.h>
#define MIN -65535
int findMaxInTreeNonRecursive(struct binaryTreeNode * root)
{
	// Initialize max with a very less value;
	int max = MIN;

	// Level Order Traversal
	struct binaryTreeNode * temp = NULL;
	struct queue * Q = NULL;
	if(root == NULL)
		return;

	Q = enQueue(Q, root);

	while(!isQueueEmpty(Q))
	{
		temp = Q -> front -> data;

		Q = deQueue(Q);

		// Find the max value
		if(temp -> data > max)
			max = temp -> data;

		if(temp -> left)
			Q = enQueue(Q, temp -> left);
		if(temp -> right)
			Q = enQueue(Q, temp -> right);
	}
	free(Q);

	return max;
}

Time Complexity:- O(n)
Space Complexity:- O(n)

You can download the complete working code here. Use your favorite editor to open it.

Ideone link:- http://ideone.com/7GvTS5