PreOrder binary tree.cpp

/*
Preorder Binary Tree
You are given the root node of a binary tree. Print its preorder traversal.

Input Format:
The first and the only line of input will contain the node data, all separated by a single space. Since -1 is used as an indication whether the left or 
right node data exist for root, it will not be a part of the node data.

Output Format:
The only line of output prints the preorder traversal of the given binary tree.

Constraints:
1 <= N <= 10^6
Where N is the total number of nodes in the binary tree.

Time Limit: 1 sec

Sample Input 1:
1 2 3 4 5 6 7 -1 -1 -1 -1 -1 -1 -1 -1

Sample Output 1:
1 2 4 5 3 6 7


Sample Input 2:
5 6 10 2 3 -1 -1 -1 -1 -1 9 -1 -1

Sample Output 2:
5 6 2 3 9 10
*/

/***********************************************************
	Following is the Binary Tree Node class structure

	template <typename T>
	class BinaryTreeNode {
    	public : 
    	T data;
    	BinaryTreeNode<T> *left;
    	BinaryTreeNode<T> *right;

    	BinaryTreeNode(T data) {
        	this -> data = data;
        	left = NULL;
        	right = NULL;
    	}
	};

************************************************************/

void preOrder(BinaryTreeNode<int> *root) {
	// Write your code here
    if(root == NULL) {
        return;
    }
    
	cout << root -> data << " ";
    preOrder(root -> left);
    preOrder(root -> right);
}