二叉树的遍历：递归，非递归

最新推荐文章于 2025-06-07 18:58:35 发布

huangjingjinglll

最新推荐文章于 2025-06-07 18:58:35 发布

阅读量274

点赞数

CC 4.0 BY-SA版权

分类专栏：编程题

本文链接：https://blog.youkuaiyun.com/huangjingjinglll/article/details/104693733

编程题专栏收录该内容

20 篇文章

订阅专栏

本文深入探讨了二叉树的前序、中序和后序遍历算法，包括递归和非递归实现方式。详细解释了每种遍历方法的原理，并提供了具体的Java代码实现，帮助读者理解二叉树的遍历过程。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

public class Tree {
	
	public class Node{
		public Node left;
		public Node right;
		public int val;
		
		public Node(int val) {
			this.val = val;
		}
		
	}
	//前序递归
	public void preOrderRecur(Node head) {
		if(head == null) {
			return;
		}
		System.out.println(head.val);
		preOrderRecur(head.left);
		preOrderRecur(head.right);
	}
	
	//中序递归
	public void inOrderRecur(Node head) {
		if(head == null) {
			return;
		}
		inOrderRecur(head.left);
		System.out.println(head.val);
		inOrderRecur(head.right);

	}
	//后序递归
	public void postOrderRecur(Node head) {
		if(head == null) {
			return;
		}
		postOrderRecur(head.left);
		postOrderRecur(head.right);
		System.out.println(head.val);
	}
	
	//前序非递归,先弹，加右，加左
	public void preOrderUnRecur(Node head) {
		if(head!=null) {
			Stack<Node> stack = new Stack<Node>();
			stack.add(head);
			while(!stack.isEmpty()) {
				head = stack.pop();
				if(head.right!=null) {
					stack.add(head.right);
				}
				if(head.left!=null) {
					stack.push(head.right);
				}
			}
		}
	}
	
	//中序非递归,左 root 右
	public void inOrderUnRecur(Node head) {
		if(head!=null) {
			Stack<Node> stack = new Stack<Node>();
			while(!stack.isEmpty()|| head !=null){
				if(head !=null) {
					stack.push(head);
					head = head.left;
				}else {
					head = stack.pop();
					System.out.println(head.val);
					head = head.right;
				}
			}
		}
	}
	
   //后续非递归  left right root
	public void postOrderUnRecur(Node head) {
		if(head != null) {
			Stack<Node> s1 = new Stack<Node>();
			Stack<Node> s2 = new Stack<Node>();
			s1.add(head);
			while(!s1.isEmpty()) {
				head = s1.pop();
				s2.push(head);
				if(head.left!=null) {
					s1.push(head.left);
				}
				if(head.right!=null) {
					s1.push(head.right);
				}
				
			}
			while(!s2.isEmpty()) {
				head = s2.pop();
				System.out.println(head.val);
			}
		}
	}
		
	
	

}