Binarytree.cpp

// C++ program to implement iterative preorder traversal in Binary trees
#include<iostream>
#include<stack>
using namespace std;

struct node {
	int data;
	struct node* left;
	struct node* right;
};

struct node* newNode(int data)
{
	struct node* node = new struct node;
	node->data = data;
	node->left = NULL;
	node->right = NULL;
	return (node);
}

// An iterative process to print preorder traversal of Binary tree
void iterativePreorder(node* root)
{
	// Base Case
	if (root == NULL)
		return;

	// Create an empty stack and push root to it
	stack<node*> nodeStack;
	nodeStack.push(root);

	/* Pop all items one by one. Do following for every popped item
	a) print it
	b) push its right child
	c) push its left child
	Note that right child is pushed first so that left is processed first */
	while (nodeStack.empty() == false) {
		// Pop the top item from stack and print it
		struct node* node = nodeStack.top();
		printf("%d ", node->data);
		nodeStack.pop();

		// Push right and left children of the popped node to stack
		if (node->right)
			nodeStack.push(node->right);
		if (node->left)
			nodeStack.push(node->left);
	}
}




// Driver program to test above functions
int main()
{
	/* Constructed binary tree is
		 10
		/  \
	   8    2
	  / \   /
	3	 5 2
*/
	struct node* root = newNode(10);
	root->left = newNode(8);
	root->right = newNode(2);
	root->left->left = newNode(3);
	root->left->right = newNode(5);
	root->right->left = newNode(2);
	iterativePreorder(root);
	return 0;
}