import java.util.Stack;
/**
* IteratorTraversal
*/
public class IteratorTraversal {
/**
* 前序遍历
* @param root
*/
public void preOrder(TreeNode root) {
Stack<TreeNode> stack = new Stack<>();
if (root == null) {
return;
}
stack.push(root);
while (!stack.empty()) {
TreeNode currentNode = stack.pop();
if (currentNode != null) {
System.out.print(currentNode.val + " ");
stack.push(currentNode.right);
stack.push(currentNode.left);
}
}
}
/**
* 中序遍历
* @param root
*/
public void inOrder(TreeNode root) {
Stack<TreeNode> stack = new Stack<>();
if (root == null) {
return;
}
TreeNode currentNode = root;
while (currentNode != null || !stack.empty()) {
while (currentNode != null) {
stack.push(currentNode);
currentNode = currentNode.left;
}
if (!stack.empty()) {
currentNode = stack.pop();
System.out.print(currentNode.val + " ");
currentNode = currentNode.right;
}
}
}
/**
* 后续遍历
* @param root
*/
public void postOrder(TreeNode root) {
Stack<TreeNode> stack = new Stack<>();
if (root == null) {
return;
}
}
/**
* 按层遍历
* @param node
*/
public void levelOrder(TreeNode node) {
}
}
