This is a java program to construct a binary tree and perform preorder traversal of the constructed binary tree.
Nodes visited are in the order:
visit Root node
visit Left node
visit Right node
Here is the source code of the Java Program to Perform Preorder Non-Recursive Traversal of a Given Binary Tree. The Java program is successfully compiled and run on a Windows system. The program output is also shown below.
//This is a java program to implement non recursive pre-order traversal of Binary Search Tree import java.util.Scanner; import java.util.Stack; class BinarySearchTreeNode { BinarySearchTreeNode left, right; int data; public BinarySearchTreeNode() { left = null; right = null; data = 0; } public BinarySearchTreeNode(int n) { left = null; right = null; data = n; } public void setLeft(BinarySearchTreeNode n) { left = n; } public void setRight(BinarySearchTreeNode n) { right = n; } public BinarySearchTreeNode getLeft() { return left; } public BinarySearchTreeNode getRight() { return right; } public void setData(int d) { data = d; } public int getData() { return data; } } class BinarySearchTreeOperations { private BinarySearchTreeNodes root; public BinarySearchTreeOperations() { root = null; } public boolean isEmpty() { return root == null; } public void insert(int data) { root = insert(root, data); } private BinarySearchTreeNodes insert(BinarySearchTreeNodes node, int data) { if (node == null) node = new BinarySearchTreeNodes(data); else { if (data <= node.getData()) node.left = insert(node.left, data); else node.right = insert(node.right, data); } return node; } public void preorder() { preorder(root); } private void preorder(BinarySearchTreeNodes r) { Stack<BinarySearchTreeNodes> s = new Stack<BinarySearchTreeNodes>(); s.push(r); while (!s.empty()) { r = s.pop(); System.out.print(r.data + " "); if (r.right != null) s.push(r.right); if (r.left != null) s.push(r.left); } } } public class Preorder_NonRecursive_BST { public static void main(String[] args) { Scanner scan = new Scanner(System.in); BinarySearchTreeOperations bst = new BinarySearchTreeOperations(); System.out.println("Enter the first 10 elements of the tree\n"); int N = 10; for (int i = 0; i < N; i++) bst.insert(scan.nextInt()); System.out.print("\nPre order : "); bst.preorder(); scan.close(); } }
Output:
$ javac Preorder_NonRecursive_BST.java $ java Preorder_NonRecursive_BST Enter the first 10 elements of the tree 12 4 10 13 15 46 78 98 45 12 Pre order : 12 4 10 12 13 15 46 45 78 98
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