Java实现树的遍历（前序、中序、后续（递归|非递归）、层次）

最新推荐文章于 2024-04-12 18:08:20 发布

转载最新推荐文章于 2024-04-12 18:08:20 发布 · 2.4k 阅读

文章标签：

#java #数据结构 #树 #遍历

java 同时被 2 个专栏收录

13 篇文章

订阅专栏

面试

8 篇文章

订阅专栏

本文深入探讨了二叉树的遍历方法，包括递归与非递归的前序、中序、后序遍历，以及层次遍历。通过具体代码实现，详细解释了每种遍历方式的工作原理。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

package com.zeph.bp;

import java.util.LinkedList;
import java.util.Queue;
import java.util.Stack;

public class Tree {
private BinaryTreeNode root;

// 递归中序遍历
public void inOrder(BinaryTreeNode current) {
	if (current != null) {
		inOrder(current.llink);
		System.out.print(current.info);
		inOrder(current.rlink);
	}
}

// 非递归中序遍历
public void nonRecursiveInOrder() {
	Stack<BinaryTreeNode> stack = new Stack<BinaryTreeNode>();
	BinaryTreeNode current;
	current = root;
	while ((current != null) || (!stack.empty())) {
		if (current != null) {
			stack.push(current);
			current = current.llink;
		} else {
			current = (BinaryTreeNode) stack.peek();
			stack.pop();
			System.out.print(current.info);
			current = current.rlink;
		}
	}
}

// 递归前序遍历
public void preOrder(BinaryTreeNode current) {
	if (current != null) {
		System.out.print(current.info);
		preOrder(current.llink);
		preOrder(current.rlink);
	}
}

// 非递归前序遍历
public void nonRecursivePreOrder() {
	Stack<BinaryTreeNode> stack = new Stack<BinaryTreeNode>();
	BinaryTreeNode current;
	current = root;
	while ((current != null) || (!stack.isEmpty())) {
		if (current != null) {
			System.out.print(current.info);
			stack.push(current);
			current = current.llink;
		} else {
			current = (BinaryTreeNode) stack.peek();
			stack.pop();
			current = current.rlink;
		}
	}
}

// 递归后序遍历
public void postOrder(BinaryTreeNode current) {
	if (current != null) {
		postOrder(current.llink);
		postOrder(current.rlink);
		System.out.print(current.info);
	}
}

// 非递归后序遍历
public void notRecursivePostOrder() {
	Stack<BinaryTreeNode> stack = new Stack<BinaryTreeNode>();
	BinaryTreeNode current;
	current = root;
	while ((current != null) || (!stack.isEmpty())) {
		if (current != null) {
			current.isFirst = true;
			stack.push(current);
			current = current.llink;
		} else {
			current = stack.peek();
			stack.pop();
			if (current.isFirst) {
				current.isFirst = false;
				stack.push(current);
				current = current.rlink;
			} else {
				System.out.print(current.info);
				current = null;
			}
		}
	}
}

// 树的层次遍历
public void bfs() {
	Queue<BinaryTreeNode> queue = new LinkedList<BinaryTreeNode>();
	BinaryTreeNode current;
	current = root;
	while ((current != null) || (!queue.isEmpty())) {
		if (current != null) {
			System.out.print(current.info);
			queue.add(current.llink);
			queue.add(current.rlink);
			current = queue.poll();
		} else {
			current = queue.poll();
		}
	}
}

public class BinaryTreeNode {
	private BinaryTreeNode llink = null;
	private BinaryTreeNode rlink = null;
	private int info;
	private boolean isFirst;

	public BinaryTreeNode(int info) {
		this.info = info;
	}
}

public void initTree() {
	root = new BinaryTreeNode(1);
	root.llink = new BinaryTreeNode(2);
	root.rlink = new BinaryTreeNode(3);
	root.llink.llink = null;
	root.llink.rlink = new BinaryTreeNode(4);
}

public BinaryTreeNode getRoot() {
	return root;
}

public void setRoot(BinaryTreeNode root) {
	this.root = root;
}

public static void main(String[] args) {
	Tree tree = new Tree();
	tree.initTree();
	// tree.preOrder(tree.getRoot());
	// tree.nonRecursivePreOrder();
	// tree.inOrder(tree.getRoot());
	// tree.nonRecursiveInOrder();
	// tree.postOrder(tree.getRoot());
	// tree.notRecursivePostOrder();
	tree.bfs();
}

}

作者：benw1988
来源：优快云
原文：https://blog.youkuaiyun.com/benweizhu/article/details/7930697
版权声明：本文为博主原创文章，转载请附上博文链接！