二叉搜索树的实现

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

public class BST<Key extends Comparable<Key>, Value> {
    private Node root;

    public class Node {
        private Key key;
        private Value val;
        private Node parent, left, right;
        private int height;

        private Node(Key key, Value val, int height, Node parent) {
            this.key = key;
            this.val = val;
            this.height = height;
            this.parent = parent;
            this.left = this.right = null;
        }
    }

    public int size(Node x) {
        return x.height;
    }

    private void UpdateHeight(Node x) {
        while (true) {
            if (x.left == null && x.right == null) {
            } else if (x.left == null)
                x.height = x.right.height + 1;
            else if (x.right == null)
                x.height = x.left.height + 1;
            else
                x.height = (x.left.height == x.right.height ? x.left.height : x.left.height > x.right.height ? x.left.height : x.right.height) + 1;
            if (x.parent == null)
                break;
            else
                x = x.parent;
        }
        root = x;
    }

    public int Search(Key key) {
        return SearchIn(root, key);
    }

    private int SearchIn(Node t, Key key) {
        if (t == null)
            return 0;
        else if (key.compareTo(t.key) == 0)
            return t.height;
        return SearchIn(key.compareTo(t.key) < 0 ? t.left : t.right, key);
    }


    public void Insert(Key key, Value val) {
        if (root == null)
            root = new Node(key, val, 0, null);
        Node temp = root;
        while (true) {
            int cmp = key.compareTo(temp.key);
            if (cmp < 0) {
                if (temp.left == null) {
                    temp.left = new Node(key, val, 0, temp);
                    UpdateHeight(temp);
                    return;
                } else
                    temp = temp.left;
            } else if (cmp > 0) {
                if (temp.right == null) {
                    temp.right = new Node(key, val, 0, temp);
                    UpdateHeight(temp);
                    return;
                } else
                    temp = temp.right;
            } else {
                temp.val = val;
                return;
            }
        }
    }

    public Node Remove(Key key) {
        Node temp_root = root;
        if (root == null || key == null)
            return null;
        while (temp_root != null) {
            int cmp = key.compareTo(temp_root.key);
            if (cmp > 0)
                temp_root = temp_root.right;
            else if (cmp < 0)
                temp_root = temp_root.left;
            else {
                if (temp_root.left == null || temp_root.right == null) {
                    if (temp_root.left != null) {
                        temp_root.key = temp_root.left.key;
                        temp_root.val = temp_root.left.val;
                        temp_root.left = temp_root.left.left;
                        temp_root.right = temp_root.left.right;
                    } else if (temp_root.right != null) {
                        temp_root.key = temp_root.right.key;
                        temp_root.val = temp_root.right.val;
                        temp_root.left = temp_root.right.left;
                        temp_root.right = temp_root.right.right;
                    } else {
                        temp_root = temp_root.parent;
                        if (temp_root.left != null && temp_root.left.key == key)
                            temp_root.left = null;
                        else
                            temp_root.right = null;
                    }
                    UpdateHeight(temp_root);
                } else {
                    Node t = temp_root.right;
                    while (t.left != null)
                        t = t.left;
                    temp_root.key = t.key;
                    temp_root.val = t.val;
                    if (t.right != null) {
                        t.key = t.right.key;
                        t.val = t.right.val;
                        t.left = t.right.left;
                        t.right = t.right.right;
                    } else {
                        t.parent.left = null;
                    }
                    UpdateHeight(t);
                }
                return root;
            }
        }
        return root;
    }

    public Queue<Key> Inorder() {                    //先序遍历
        Queue<Key> keys = new LinkedList<>();
        Stack<Node> stack = new Stack<Node>();
        stack.push(root);
        Node node = root;
        while (true) {
            if (node != null) {
                stack.push(node);
                node = node.left;
            } else if (!stack.isEmpty()) {
                node = stack.pop();
                keys.offer(node.key);
                node = node.right;
            } else
                break;
        }
        return keys;
    }

    public Queue<Key> LevelOrder() {                    //层次遍历
        Queue<Key> keys = new LinkedList<Key>();
        Queue<Node> nodes = new LinkedList<Node>();
        Node node = root;
        nodes.offer(node);
        while (!nodes.isEmpty()) {
            Node x = ((LinkedList<Node>) nodes).pop();
            keys.offer(x.key);
            if (x.left != null)
                nodes.offer(x.left);
            if (x.right != null)
                nodes.offer(x.right);
        }
        return keys;
    }

    public static void main(String args[]) {
        BST<Integer, Integer> tt = new BST<Integer, Integer>();
        for (int i = 0; i < 10; i++) {
            int x = (int) (Math.random() * 50);
            tt.Insert(x, i);
            System.out.println(x);
        }
        for (Integer i : tt.LevelOrder())
            System.out.println(i + " : " + tt.Search(i));
        tt.Remove(30);
        System.out.println("---------------------");
        for (Integer i : tt.LevelOrder())
            System.out.println(i + " : " + tt.Search(i));
        System.out.println("断点设置处");
    }
}