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Java实现非递归遍历二叉树
import java.util.LinkedList;
import java.util.Queue;
import java.util.Stack;
public class Tree>
{
private static class BinaryNode
{
BinaryNode(AnyType theElement)
{
this(theElement, null, null);
}BinaryNode(AnyType theElement, BinaryNode lt, BinaryNode rt)
{
element = theElement;
left = lt;
right = rt;
}AnyType element;
BinaryNode left;
BinaryNode right;
}private BinaryNode root;
public void insert(AnyType x)
{
root = insert(x, root);
}public boolean isEmpty()
{
return root == null;
}private BinaryNode insert(AnyType x, BinaryNode t)
{
if(t == null)
{
return new BinaryNode<>(x, null, null);
}int compareResult = x.compareTo(t.element);
if(compareResult < 0)
{
t.left = insert(x, t.left);
}
else if(compareResult > 0)
{
t.right = insert(x, t.right);
}
else
{
;
}return t;
}/**
* 前序遍历
* 递归
*/
public void preOrder(BinaryNode Node)
{
if (Node != null)
{
System.out.print(Node.element + " ");
preOrder(Node.left);
preOrder(Node.right);
}
}/**
* 中序遍历
* 递归
*/
public void midOrder(BinaryNode Node)
{
if (Node != null)
{
midOrder(Node.left);
System.out.print(Node.element + " ");
midOrder(Node.right);
}
}/**
* 后序遍历
* 递归
*/
public void posOrder(BinaryNode Node)
{
if (Node != null)
{
posOrder(Node.left);
posOrder(Node.right);
System.out.print(Node.element + " ");
}
}/*
* 层序遍历
* 递归
*/
public void levelOrder(BinaryNode Node) {
if (Node == null) {
return;
}int depth = depth(Node);
for (int i = 1;
i <= depth;
i++) {
levelOrder(Node, i);
}
}private void levelOrder(BinaryNode Node, int level) {
if (Node == null || level < 1) {
return;
}if (level == 1) {
System.out.print(Node.element + "");
return;
}// 左子树
levelOrder(Node.left, level - 1);
// 右子树
levelOrder(Node.right, level - 1);
}public int depth(BinaryNode Node) {
if (Node == null) {
return 0;
}int l = depth(Node.left);
int r = depth(Node.right);
if (l > r) {
return l + 1;
} else {
return r + 1;
}
}/**
* 前序遍历
* 非递归
*/
public void preOrder1(BinaryNode Node)
{
Stack stack = new Stack<>();
while(Node != null || !stack.empty())
{
while(Node != null)
{
System.out.print(Node.element + "");
stack.push(Node);
Node = Node.left;
}
if(!stack.empty())
{
Node = stack.pop();
Node = Node.right;
}
}
}/**
* 中序遍历
* 非递归
*/
public void midOrder1(BinaryNode Node)
{
Stack stack = new Stack<>();
while(Node != null || !stack.empty())
{
while (Node != null)
{
stack.push(Node);
Node = Node.left;
}
if(!stack.empty())
{
Node = stack.pop();
System.out.print(Node.element + "");
Node = Node.right;
}
}
}/**
* 后序遍历
* 非递归
*/
public void posOrder1(BinaryNode Node)
{
Stack stack1 = new Stack<>();
Stack stack2 = new Stack<>();
int i = 1;
while(Node != null || !stack1.empty())
{
while (Node != null)
{
stack1.push(Node);
stack2.push(0);
Node = Node.left;
}while(!stack1.empty() && stack2.peek() == i)
{
stack2.pop();
System.out.print(stack1.pop().element + "");
}if(!stack1.empty())
{
stack2.pop();
stack2.push(1);
Node = stack1.peek();
Node = Node.right;
}
}
}/*
* 层序遍历
* 非递归
*/
public void levelOrder1(BinaryNode Node) {
if (Node == null) {
return;
}BinaryNode binaryNode;
Queue queue = new LinkedList<>();
queue.add(Node);
while (queue.size() != 0) {
binaryNode = queue.poll();
System.out.print(binaryNode.element + "");
if (binaryNode.left != null) {
queue.offer(binaryNode.left);
}
if (binaryNode.right != null) {
queue.offer(binaryNode.right);
}
}
}public static void main( String[] args )
{
int[] input = {4, 2, 6, 1, 3, 5, 7, 8, 10};
Tree tree = new Tree<>();
for(int i = 0;
i < input.length;
i++)
{
tree.insert(input[i]);
}
System.out.print("递归前序遍历 ：");
tree.preOrder(tree.root);
System.out.print("\n非递归前序遍历：");
tree.preOrder1(tree.root);
System.out.print("\n递归中序遍历 ：");
tree.midOrder(tree.root);
System.out.print("\n非递归中序遍历 ：");
tree.midOrder1(tree.root);
System.out.print("\n递归后序遍历 ：");
tree.posOrder(tree.root);
System.out.print("\n非递归后序遍历 ：");
tree.posOrder1(tree.root);
System.out.print("\n递归层序遍历：");
tree.levelOrder(tree.root);
System.out.print("\n非递归层序遍历 ：");
tree.levelOrder1(tree.root);
}
}
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