Iterative Binary Tree Traversals

Iterative PreOrder traversal of a Binary Tree:

private void preOrderIterative(Node node) {

Stack stack = new Stack();

while (node != null || !stack.isEmpty()) {

if (null == node) {

node = stack.pop();

}

System.out.print(node.data + " -> ");

if (node.right != null) {

stack.push(node.right);

}

node = node.left;

}

}

Iterative InOrder traversal of a Binary Tree:

private void inorderIterative(Node node) {

Stack stack = new Stack();

while (node != null || !stack.isEmpty()) {

if (null == node) {

node = stack.pop();

System.out.print(node.data + " -> ");

node = node.right;

}

if (node != null) {

stack.push(node);

node = node.left;

}

}

}

Iterative PostOrder traversal of a Binary Tree:

private void preorderIterative(Node node) {

Stack stack = new Stack();

while (node != null || !stack.isEmpty()) {

if (node == null) {

while (!stack.isEmpty() && (node == stack.peek().right)) {

node = stack.pop();

System.out.print(node.data + " -> ");

}

node = stack.isEmpty()? null : stack.peek().right;

}

if (node != null) {

stack.push(node);

node = node.left;

}

}

}