二叉树的三种遍历（先序遍历，中序遍历，后续遍历）-JAVA语言实现

红太狼 2023-06-09 10:28 15阅读 0赞

二叉树的三种遍历方式，递归实现。

public class TreeNode {
        int value;
        TreeNode leftNode;
        TreeNode rightNode;
    
        public TreeNode(int value){
            this.value = value;
        }
    
    
        public void setLeftNode(TreeNode leftNode) {
            this.leftNode = leftNode;
        }
    
    
        public void setRightNode(TreeNode rightNode) {
            this.rightNode = rightNode;
        }
    
        //前序遍历
        public void preOrder(){
            System.out.println(value);
            if (leftNode != null){
                leftNode.preOrder();
            }
            if (rightNode != null){
                rightNode.preOrder();;
            }
        }
        //中序遍历
        public void midOrder(){
            if (leftNode != null){
                leftNode.midOrder();
            }
            System.out.println(value);
            if (rightNode != null){
                rightNode.midOrder();;
            }
        }
        //后序遍历
        public void postOrder(){
            if (leftNode != null){
                leftNode.postOrder();
            }
            if (rightNode != null){
                rightNode.postOrder();;
            }
            System.out.println(value);
        }
    }

public class BinaryTree {
        TreeNode root;
    
        public void setRoot(TreeNode root) {
            this.root = root;
        }
    
        public TreeNode getRoot() {
            return root;
        }
    
        //前序遍历
        public void preOrder(){
         if (root != null)
            root.preOrder();
        }
        //中序遍历
        public void midOrder(){
         if (root != null)
            root.midOrder();
        }
        //后序遍历
        public void postOrder(){
         if (root != null)
            root.postOrder();
        }
    }

public class TestBinaryTree {
        public static void main(String[] args) {
            BinaryTree binaryTree = new BinaryTree();
            //创建第一层根节点
            TreeNode root = new TreeNode(1);
            binaryTree.setRoot(root);
    
            //创建第二层节点
            TreeNode leftNode2 = new TreeNode(2);
            root.setLeftNode(leftNode2);
            TreeNode rightNode2 = new TreeNode(3);
            root.setRightNode(rightNode2);
    
            //创建第3层节点
            leftNode2.setLeftNode(new TreeNode(4));
            leftNode2.setRightNode(new TreeNode(5));
    
            rightNode2.setLeftNode(new TreeNode(6));
            rightNode2.setRightNode(new TreeNode(7));
    
            System.out.println("先序遍历:");
            binaryTree.preOrder();
    
            System.out.println("中序遍历:");
            binaryTree.midOrder();
    
            System.out.println("后序遍历:");
            binaryTree.postOrder();
    
    
        }
    }