二叉树遍历实战

短命女 2021-07-24 20:53 325阅读 0赞

# 一 需求 #

实现二叉树的前序、中序和后序遍历。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoZW5ncWl1bWluZw_size_16_color_FFFFFF_t_70][]

# 二 算法说明 #

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoZW5ncWl1bWluZw_size_16_color_FFFFFF_t_70 1][]

# 三 代码 #

/**
    * @className: BinaryTreeDemo
    * @description: 二叉树实战
    * @date: 2021/3/16
    * @author: cakin
    */
    public class BinaryTreeDemo {
       /**
        * 功能描述：二叉树测试
        *
        * @author cakin
        * @date 2021/3/16
        * @param args 命令行
        */
        public static void main(String[] args) {
            // 创建一颗二叉树
            BinaryTree binaryTree = new BinaryTree();
            // 创建需要的结点
            HeroNode root = new HeroNode(1, "宋江");
            HeroNode node2 = new HeroNode(2, "吴用");
            HeroNode node3 = new HeroNode(3, "卢俊义");
            HeroNode node4 = new HeroNode(4, "林冲");
            HeroNode node5 = new HeroNode(5, "关胜");
    
    
            // 先手动创建该二叉树
            root.setLeft(node2);
            root.setRight(node3);
            node3.setRight(node4);
            node3.setLeft(node5);
            binaryTree.setRoot(root);
    
    
           System.out.println("前序遍历"); // 1,2,3,5,4
           binaryTree.preOrder();
    
           System.out.println("中序遍历");
           binaryTree.infixOrder(); // 2,1,5,3,4
    
           System.out.println("后序遍历");
           binaryTree.postOrder(); // 2,5,4,3,1
        }
    }
    
    /**
    * @className: BinaryTreeDemo
    * @description: 二叉树
    * @date: 2021/3/16
    * @author: cakin
    */
    class BinaryTree {
        private HeroNode root;
    
        public void setRoot(HeroNode root) {
            this.root = root;
        }
    
       /**
        * 功能描述：前序遍历
        *
        * @author cakin
        * @date 2021/3/16
        */
        public void preOrder() {
            if (this.root != null) {
                this.root.preOrder();
            } else {
                System.out.println("二叉树为空，无法遍历");
            }
        }
    
       /**
        * 功能描述：中序遍历
        *
        * @author cakin
        * @date 2021/3/16
        */
        public void infixOrder() {
            if (this.root != null) {
                this.root.infixOrder();
            } else {
                System.out.println("二叉树为空，无法遍历");
            }
        }
    
       /**
        * 功能描述：后序遍历
        *
        * @author cakin
        * @date 2021/3/16
        */
        public void postOrder() {
            if (this.root != null) {
                this.root.postOrder();
            } else {
                System.out.println("二叉树为空，无法遍历");
            }
        }
    }
    
    /**
    * @className: HeroNode
    * @description: 英雄节点
    * @date: 2021/3/16
    * @author: cakin
    */
    class HeroNode {
        private int no;
        private String name;
        private HeroNode left; // 默认null
        private HeroNode right; // 默认null
    
        public HeroNode(int no, String name) {
            this.no = no;
            this.name = name;
        }
    
        public int getNo() {
            return no;
        }
    
        public void setNo(int no) {
            this.no = no;
        }
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public HeroNode getLeft() {
            return left;
        }
    
        public void setLeft(HeroNode left) {
            this.left = left;
        }
    
        public HeroNode getRight() {
            return right;
        }
    
        public void setRight(HeroNode right) {
            this.right = right;
        }
    
        @Override
        public String toString() {
            return "HeroNode [no=" + no + ", name=" + name + "]";
        }
    
        /**
         * 功能描述：前序遍历
         *
         * @author cakin
         * @date 2021/3/16
         */
        public void preOrder() {
            System.out.println(this); //先输出父结点
            //递归向左子树前序遍历
            if (this.left != null) {
                this.left.preOrder();
            }
            //递归向右子树前序遍历
            if (this.right != null) {
                this.right.preOrder();
            }
        }
    
    
       /**
        * 功能描述：中序遍历
        *
        * @author cakin
        * @date 2021/3/16
        */
        public void infixOrder() {
    
    
            //递归向左子树中序遍历
            if (this.left != null) {
                this.left.infixOrder();
            }
            //输出父结点
            System.out.println(this);
            //递归向右子树中序遍历
            if (this.right != null) {
                this.right.infixOrder();
            }
        }
    
    
       /**
        * 功能描述：后序遍历
        *
        * @author cakin
        * @date 2021/3/16
        */
        public void postOrder() {
            if (this.left != null) {
                this.left.postOrder();
            }
            if (this.right != null) {
                this.right.postOrder();
            }
            System.out.println(this);
        }
    }

# 四 测试 #

前序遍历
    HeroNode [no=1, name=宋江]
    HeroNode [no=2, name=吴用]
    HeroNode [no=3, name=卢俊义]
    HeroNode [no=5, name=关胜]
    HeroNode [no=4, name=林冲]
    中序遍历
    HeroNode [no=2, name=吴用]
    HeroNode [no=1, name=宋江]
    HeroNode [no=5, name=关胜]
    HeroNode [no=3, name=卢俊义]
    HeroNode [no=4, name=林冲]
    后序遍历
    HeroNode [no=2, name=吴用]
    HeroNode [no=5, name=关胜]
    HeroNode [no=4, name=林冲]
    HeroNode [no=3, name=卢俊义]
    HeroNode [no=1, name=宋江]

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