Java实现红黑树

1.左旋:让x的左子节点变为h的右子节点
h.right = h.left
2.让h成为x的左子节点
x.left = h;
3.让h的color属性变为x的color属性值
x.color = h.color
4.让h的color属性变为red
h.color = true

向单个节点插入节点,插入节点小于当前节点

插入节点大于当前节点需要进行右旋

原始的红黑树

向底部的2-节点插入新的键

左旋后

颜色反转后

向一颗双键树中插入新键
1.新键大于原树中的两个键

2.新键大于原树中的一个键小于另一个键

向树底部3-节点插入新键

public class RedBlackTree,V> {
    private Node root;
    private int N;
    public static final boolean RED = true;
    public static final boolean BLACK = false;
    private class Node{
        K key;
        V value;
        Node left;
        Node right;
        boolean color;

        public Node(K key, V value, Node left, Node right, boolean color) {
            this.key = key;
            this.value = value;
            this.left = left;
            this.right = right;
            this.color = color;
        }
    }
    public int size(){
        return N;
    }

    
    public boolean isRed(Node x){
        if(x==null) return false;
        return x.color == RED;
    }
    //左旋
    public Node rotateLeft(Node h){
        //获取h节点右子节点表示为x
        Node x = h.right;
        //让x节点的左子节点成为h节点的右子节点
        h.right = x.left;
        //让h成为x的左子节点
        x.left = h;
        //让x节点的color属性等于h节点的color书属性
        x.color = h.color;
        //让h节点的color属性变为红色
        h.color = RED;
        return x;
    }
    public Node roltateRight(Node h){
       //获取h节点的左子节点表示x
        Node x = h.left;
        //x节点的右子节点成为h节点的左子节点
        h.left = x.right;
        //让h节点成为x节点的右子树
        x.right = h;
        //让x节点的color属性等于h节点的color属性
        x.color = h.color;
        //让h节点color为红色
        h.color = RED;
        return x;
    }
    //颜色反转
    public void flipColors(Node h){
        h.color = RED;
        h.left.color=BLACK;
        h.right.color=BLACK;
    }
    public void put(K key,V value){
        root = put(root,key,value);
        root.color = BLACK;
    }

    private Node put(Node h, K key, V value) {
        N++;
        if(h==null){

            return new Node(key,value,null,null,RED);
        }
        //比较h节点和key的值
        int cmp = key.compareTo(h.key);
        if(cmp<0){
            h.left =  put(h.left,key,value);
        }else if(cmp>0){
            h.right = put(h.right,key,value);
        }else{
            h.value = value;
        }
        //当前节点h的节点左子节点为黑色,h节点的右子树为红色
        if(isRed(h.right)&&!isRed(h.left)){
              h = rotateLeft(h);
        }
        //当前节点的左子树的左子树都为红色,则需要进行右旋
        if(isRed(h.left)&&isRed(h.left.left)){
            h = roltateRight(h);
        }
        //颜色反转
        //当前节点的左子节点和右自己节点都以为红色则尽心颜色反转
        if(isRed(h.left)&&isRed(h.right)){
            flipColors(h);
        }
        return h;
    }
   public V get(K key){
        return get(root,key);
   }

    private V get(Node x, K key) {
        if(x==null){
            return null;
        }
        int cmp = key.compareTo(x.key);
        if(cmp<0){
            return get(x.left,key);
        }else if(cmp>0){
            return get(x.right,key);
        }else {
            return x.value;
        }
    }

    public static void main(String[] args) {
        RedBlackTree tree = new RedBlackTree<>();
        tree.put("1","张三");
        tree.put("2","李四");
        tree.put("3","王五");
        //从树中获取元素
        String r1 = tree.get("1");
        System.out.println(r1);
        String r2 = tree.get("2");
        System.out.println(r2);
        String r3 = tree.get("3");
        System.out.println(r3);
        

        
    }


}