Java代码实现构造一颗三叉链表表示的二叉树，实现创建方法体在二叉树中查找一个结点

以下是Java代码实现构造一颗三叉链表表示的二叉树，以及在二叉树中查找一个结点的方法：

class TreeNode {
    int val;
    TreeNode left;
    TreeNode right;
    TreeNode parent;

    public TreeNode(int val) {
        this.val = val;
        this.left = null;
        this.right = null;
        this.parent = null;
    }
}

class ThreeLinkBinaryTree {
    private TreeNode root;

    public ThreeLinkBinaryTree() {
        this.root = null;
    }

    public void createTree(int[] arr) {
        for (int i = 0; i < arr.length; i++) {
            insert(arr[i]);
        }
    }

    private void insert(int val) {
        TreeNode newNode = new TreeNode(val);

        if (root == null) {
            root = newNode;
        } else {
            TreeNode current = root;
            TreeNode parent;

            while (true) {
                parent = current;
                if (val < current.val) {
                    current = current.left;
                    if (current == null) {
                        parent.left = newNode;
                        newNode.parent = parent;
                        return;
                    }
                } else {
                    current = current.right;
                    if (current == null) {
                        parent.right = newNode;
                        newNode.parent = parent;
                        return;
                    }
                }
            }
        }
    }

    public TreeNode findNode(int val) {
        TreeNode current = root;

        while (current != null && current.val != val) {
            if (val < current.val) {
                current = current.left;
            } else {
                current = current.right;
            }
        }

        return current;
    }
}

使用示例：

public static void main(String[] args) {
    int[] arr = { 5, 2, 8, 1, 4, 6, 9 };
    ThreeLinkBinaryTree tree = new ThreeLinkBinaryTree();
    tree.createTree(arr);

    TreeNode node = tree.findNode(4);
    if (node != null) {
        System.out.println("找到了节点：" + node.val);
    } else {
        System.out.println("未找到节点");
    }
}