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Copy pathTreeDepthFirstTraversalIterably.java
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84 lines (65 loc) · 2.17 KB
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package com.hellokoding.algorithm;
import com.hellokoding.datastructure.BSTByLinkedList;
import java.util.ArrayDeque;
import java.util.Deque;
public class TreeDepthFirstTraversalIterably extends BSTByLinkedList {
public void preTraversal(Node node) {
if (node == null) return;
Deque<Node> stack = new ArrayDeque<>();
stack.push(node);
while (!stack.isEmpty()) {
Node currentNode = stack.pop();
System.out.println(currentNode);
if (currentNode.right != null)
stack.push(currentNode.right);
if (currentNode.left != null)
stack.push(currentNode.left);
}
}
public void inTraversal(Node node) {
Deque<Node> stack = new ArrayDeque<>();
while (node != null) {
stack.push(node);
node = node.left;
}
while (!stack.isEmpty()) {
node = stack.pop();
System.out.println(node);
if (node.right != null)
stack.push(node.right);
}
}
public void postTraversal(Node node) {
Deque<Node> stack = new ArrayDeque<>();
while (node != null) {
stack.push(node);
node = node.left;
}
Node lastVisitedNode = null;
while (!stack.isEmpty()) {
node = stack.peek();
if (node.right != null && node.right != lastVisitedNode) {
stack.push(node.right);
} else {
System.out.println(node);
lastVisitedNode = stack.pop();
}
}
}
public static void main(String[] args) {
TreeDepthFirstTraversalIterably tree = new TreeDepthFirstTraversalIterably();
tree.insert(7);
tree.insert(2);
tree.insert(3);
tree.insert(1);
tree.insert(9);
System.out.println("Pre-order Traversal");
tree.preTraversal(tree.root);
System.out.println();
System.out.println("In-order Traversal");
tree.inTraversal(tree.root);
System.out.println();
System.out.println("Post-order Traversal");
tree.postTraversal(tree.root);
}
}