Logic & Computation Binary Tree Lecture 1
import java.lang.System;
public class binarytreenotes {
public static void main(String[] args) {
BinaryTree tree = new BinaryTree(1);
/* Following is the tree after above statement
1
/ \
null null
*/
tree.root.left = new Node(2);
tree.root.right = new Node(3);
/* 2 and 3 become left and right children of 1
1
/ \
2 3
/ \ / \
null null null null */
tree.root.left.left = new Node(4);
/* 4 becomes left child of 2
1
/ \
2 3
/ \ / \
4 null null null
/ \
null null
*/
tree.root.right.left = new Node(7);
tree.root.right.right = new Node (10);
/* 7 becomes left child of 3
10 becomes right child of 3
1
/ \
2 3
/ \ / \
4 null 7 10
/ \
null null
*/
tree.inorder(tree.root);
}
}
//The legendary gate keeper of Computer Science!!!
// Class containing left and right child
// of current node and key value
class Node {
int num;
Node left, right;
public Node(int num)
{
this.num = num;
left = right = null;
}
}
class BinaryTree
{
// Root of Binary Tree
Node root;
// Constructors
BinaryTree(int num) { root = new Node(num); }
/* Inorder traversal of a binary tree*/
/* This method is extremely useful for navigating through a binary tree,
* which you will need to know for your upcoming laboratory.
* Due to the nature of binary trees, you must use recursion to
* navigate succesfully through the tree.
* There are three ways of navigating through a tree, which are known as
* preorder, inorder, and postorder traversal
*/
//Used for copying trees in the right order.
static void preorder(Node temp)
{
if (temp == null)
return;
System.out.print(temp.num + " ");
preorder(temp.left);
preorder(temp.right);
}
//Used to reach the bottom of a tree first, then work your way upwards
static void inorder(Node temp)
{
if (temp == null)
return;
inorder(temp.left);
System.out.print(temp.num + " ");
inorder(temp.right);
}
//Used to delete trees efficiently.
static void postorder(Node temp)
{
if (temp == null)
return;
postorder(temp.left);
postorder(temp.right);
System.out.print(temp.num + " ");
}
}
