2-3 tree

最新推荐文章于 2022-09-01 06:59:32 发布
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package com.leon.cc;

import com.leon.util.Stack;

/**
 * @author : Leon
 * @since : 2013-10-9
 * @see :
 */

public class Tree {

    Node root = new Node();

    public void insert(String str) {
        Node node = search_node(root, str);
        node.insert(str);
        while (need_split(node)) {
            if (node == root) {
                node = node.split();
                root = node;
            }
            else {
                node = node.split();
            }
        }
    }

    public void delete(String str) {
        Node node = contain(str);
        Node leaf = null;
        if (!node.is_leaf()) {
            leaf = tree_successor(node, str);
            int index = node.index_item(str);
            String temp = node.values[index];
            node.values[index] = leaf.values[0];
            leaf.values[0] = temp;
        }
        else {
            leaf = node;
        }
        leaf.delete(str);
        if (leaf.item_size == 0) {
            fix(leaf);
        }
    }

    private void fix(Node n) {
        if (n.parent == null) {
            root = n.disConnect(0);
        }
        else {
            Node p = n.parent;
            int[] ary = new int[3];
            int index = p.index_child(n);
            if (has_2item_sibling(n, ary)) {
                if (p.item_size == 2) {
                    if (index == 0) {
                        if (ary[1] == 2) {
                            leftRotate(0, n);
                        }
                        else {
                            leftRotate(0, n);
                            leftRotate(1, n.parent.childs[1]);
                        }
                    }
                    else if (index == 1) {
                        if (ary[2] == 2) {
                            leftRotate(1, n);
                        }
                        else {
                            rightRotate(1, n);
                        }
                    }
                    else {
                        if (ary[1] == 2) {
                            rightRotate(2, n);
                        }
                        else {
                            rightRotate(2, n);
                            rightRotate(1, n.parent.childs[1]);
                        }
                    }
                }
                else {
                    if (index == 0) {
                        leftRotate(0, n);
                    }
                    else {
                        rightRotate(1, n);
                    }
                }
            }
            else {
                if (p.item_size == 2) {
                    if (index == 0) {
                        mergeRight(0, n);
                    }
                    else if (index == 1) {
                        mergeLeft(1, n);
                    }
                    else {
                        mergeLeft(2, n);
                    }
                }
                else {
                    if (index == 0) {
                        mergeRight(0, n);
                    }
                    else {
                        mergeLeft(1, n);
                    }
                    fix(p);
                }
            }
        }
    }

    private void mergeLeft(int i, Node n) {
        Node child = null;
        Node p = n.parent;
        if (!n.is_leaf()) {
            child = n.childs[0];
            n.delete_child(0);
        }
        p.delete_child(i);
        if (i == 1) {
            p.childs[0].insert(p.values[0]);
            p.delete(p.values[0]);
            if (child != null) {
                p.childs[0].insert_child(2, child);
            }
        }
        else {
            int sibling_size = p.item_size;
            p.childs[1].insert(p.values[sibling_size - 1]);
            p.delete(p.values[sibling_size - 1]);
            if (child != null) {
                p.childs[1].insert_child(2, child);
            }
        }
    }

    private void mergeRight(int i, Node n) {
        Node child = null;
        Node p = n.parent;
        if (!n.is_leaf()) {
            child = n.childs[0];
            n.delete_child(0);
        }
        p.delete_child(0);
        p.childs[0].insert(p.values[0]);
        p.delete(p.values[0]);
        if (child != null) {
            p.childs[0].insert_child(0, child);
        }
    }

    private boolean has_2item_sibling(Node n, int[] ary) {
        Node p = n.parent;
        ary[0] = p.childs[0].item_size;
        ary[1] = p.childs[1].item_size;
        if (p.item_size == 2) {
            ary[2] = p.childs[2].item_size;
        }
        for (int i = 0; i < ary.length; i++) {
            if (ary[i] == 2) {
                return true;
            }
        }
        return false;
    }

    private void leftRotate(int index, Node n) {
        if (index == 0) {
            n.insert(n.parent.values[0]);
            n.parent.delete(n.parent.values[0]);
            n.parent.insert(n.parent.childs[1].values[0]);
            n.parent.childs[1].delete(n.parent.childs[1].values[0]);
            if (!n.is_leaf()) {
                Node node = n.parent.childs[1].delete_child(0);
                n.insert_child(1, node);
            }
        }
        else {
            n.insert(n.parent.values[1]);
            n.parent.delete(n.parent.values[1]);
            n.parent.insert(n.parent.childs[2].values[0]);
            n.parent.childs[2].delete(n.parent.childs[2].values[0]);
            if (!n.is_leaf()) {
                Node node = n.parent.childs[2].delete_child(0);
                n.insert_child(1, node);
            }
        }

    }

    private void rightRotate(int index, Node n) {
        if (index == 2) {
            n.insert(n.parent.values[1]);
            n.parent.delete(n.parent.values[1]);
            int sibling_size = n.parent.childs[1].item_size;
            n.parent.insert(n.parent.childs[1].values[sibling_size - 1]);
            n.parent.childs[1].delete(n.parent.childs[1].values[sibling_size - 1]);
            if (!n.is_leaf()) {
                Node node = n.parent.childs[1].delete_child(sibling_size);
                n.insert_child(0, node);
            }
        }
        else {
            n.insert(n.parent.values[0]);
            n.parent.delete(n.parent.values[0]);
            int sibling_size = n.parent.childs[0].item_size;
            n.parent.insert(n.parent.childs[0].values[sibling_size - 1]);
            n.parent.childs[0].delete(n.parent.childs[0].values[sibling_size - 1]);
            if (!n.is_leaf()) {
                Node node = n.parent.childs[0].delete_child(sibling_size);
                n.insert_child(0, node);
            }
        }
    }

    public Node tree_successor(Node node, String str) {
        if (!node.is_leaf()) {
            int index = node.index_item(str);
            Node child = node.childs[index + 1];
            return tree_mins(child);
        }
        return node;
    }

    private Node tree_mins(Node child) {
        Node temp = child;
        while (!temp.is_leaf()) {
            temp = temp.childs[0];
        }
        return temp;
    }

    public Node contain(String str) {
        Node current = root;
        while (!current.contain(str)) {
            if (current.item_size == 2) {
                String small = current.values[0];
                String large = current.values[1];
                if (str.compareTo(small) < 0) {
                    current = current.childs[0];
                }
                else if (str.compareTo(small) >= 0 && str.compareTo(large) <= 0) {
                    current = current.childs[1];
                }
                else {
                    current = current.childs[2];
                }
            }
            else {
                String small = current.values[0];
                if (str.compareTo(small) < 0) {
                    current = current.childs[0];
                }
                else {
                    current = current.childs[1];
                }
            }
        }
        return current;
    }

    public boolean need_split(Node node) {
        return node.item_size > 2 ? true : false;
    }

    public Node search_node(Node node, String str) {
        if (is_leaf(node)) {
            return node;
        }
        else {
            if (node.item_size == 2) {
                String small = node.values[0];
                String large = node.values[1];
                if (str.compareTo(small) < 0) {
                    Node next = create_node(node, 0);
                    return search_node(next, str);
                }
                else if (str.compareTo(small) >= 0 && str.compareTo(large) <= 0) {
                    Node next = create_node(node, 1);
                    return search_node(next, str);
                }
                else {
                    Node next = create_node(node, 2);
                    return search_node(next, str);
                }
            }
            else {
                String small = node.values[0];
                if (str.compareTo(small) < 0) {
                    Node next = create_node(node, 0);
                    return search_node(next, str);
                }
                else {
                    Node next = create_node(node, 1);
                    return search_node(next, str);
                }
            }
        }
    }

    private Node create_node(Node node, int i) {
        Node child = node.childs[i];
        if (child == null) {
            child = new Node();
            node.childs[i] = child;
            child.parent = node;
        }
        return child;
    }

    public boolean is_leaf(Node node) {
        return node.childs[0] == null;
    }

    public static void main(String[] args) {
        Tree t = new Tree();
        String[] str = new String[] { "horse", "cow", "pig", "seal", "rat", "dog", "goat", "elephant", "fish",
                "rooster", "zebra", "roach", "cat", "hen", "llama", "aardvark", "hog", "donkey", "rhino", "hippo",
                "tiger", "lamb", "lion", "leopard", "lynx", "kitty", "ant", "ape", "animal" };
        for (int i = 0; i < str.length; i++) {
            t.insert(str[i]);
        }

        t.delete("animal");
        t.delete("aardvark");
        t.delete("cat");
        t.delete("ape");
        t.delete("donkey");
        t.delete("ant");
        t.delete("hog");
        t.delete("hen");
        t.delete("fish");
        t.delete("goat");
        t.delete("hippo");
        t.delete("kitty");
        t.delete("cow");
        t.delete("dog");
        t.delete("elephant");
        t.delete("tiger");
        t.delete("zebra");
        t.delete("horse");
        t.delete("rat");
        t.delete("rhino");
        t.delete("pig");
        t.delete("seal");
        t.delete("lynx");
        t.delete("roach");
        t.delete("lion");
        t.delete("llama");
        t.delete("lamb");
        t.delete("rooster");
        t.delete("leopard");
        String rs = t.toString();
        System.out.println(rs);
    }

    public String toString() {
        if (root == null) {
            return null;
        }
        StringBuilder sb = new StringBuilder();
        sb.append("digraph g {\n");
        sb.append("\tnode[shape = record, width = .1, height = .1];\n");
        Stack<Node> stack = new Stack<Node>();
        int k = 0;
        Stack<Integer> k_stack = new Stack<Integer>();
        stack.push(root);
        k_stack.push(k);
        sb.append("\tnode" + k + "[label = \"{<n> " + root.getName() + " }\", color = lightgray, style = filled];\n");
        while (!stack.is_empty()) {
            Node parent = stack.pop();
            String parentNode = "node" + k_stack.pop();
            for (int i = 0; i < parent.childs.length; i++) {
                if (parent.childs[i] != null) {
                    String childNode = "node" + (++k);
                    sb.append("\t" + childNode + "[label = \"{<n> " + parent.childs[i].getName()
                              + " }\", color = lightgray, style = filled];\n");
                    sb.append("\t" + parentNode + ":n->" + childNode + ":n;\n");
                    stack.push(parent.childs[i]);
                    k_stack.push(k);
                }
            }
        }
        sb.append("}\n");
        return sb.toString();
    }
}

class Node {

    String[] values = new String[3];
    int      item_size;
    Node[]   childs = new Node[4];
    Node     parent;

    public Node(String str) {
        values[0] = str;
        item_size++;
    }

    public String getName() {
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < item_size; i++) {
            sb.append(values[i] + " ");
        }
        return sb.toString();
    }

    public Node() {
    }

    public boolean contain(String str) {
        for (int i = 0; i < item_size; i++) {
            if (values[i].equals(str)) {
                return true;
            }
        }
        return false;
    }

    public int insert(String str) {
        int pos = item_size;
        for (int i = item_size - 1; i >= 0; i--) {
            if (values[i].compareTo(str) > 0) {
                values[i + 1] = values[i];
                pos = i;
            }
        }
        values[pos] = str;
        item_size++;
        return pos;
    }

    public void delete(String str) {
        int index = index_item(str);
        for (int i = index; i < item_size; i++) {
            values[i] = values[i + 1];
        }
        item_size--;
    }

    public void insert_child(int index, Node node) {
        for (int i = childs.length - 2; i >= index; i--) {
            childs[i + 1] = childs[i];
        }
        childs[index] = node;
        childs[index].parent = this;
    }

    public Node delete_child(int index) {
        Node node = childs[index];
        for (int i = index; i < childs.length - 1; i++) {
            childs[i] = childs[i + 1];
        }
        node.parent = null;
        return node;
    }

    public boolean is_leaf() {
        return childs[0] == null;
    }

    public int index_child(Node node) {
        for (int i = 0; i < childs.length; i++) {
            if (childs[i].equals(node)) {
                return i;
            }
        }
        return -1;
    }

    public int index_item(String str) {
        for (int i = 0; i < item_size; i++) {
            if (values[i].equals(str)) {
                return i;
            }
        }
        return -1;
    }

    public Node disConnect(int index) {
        Node result = childs[index];
        if (result != null) result.parent = null;
        childs[index] = null;
        return result;
    }

    public void connect(int index, Node child) {
        childs[index] = child;
        if (child != null) child.parent = this;
    }

    public Node split() {
        Node left = this;
        String middle = values[1];
        Node right = new Node(values[2]);
        left.values[1] = null;
        left.values[2] = null;
        left.item_size = 1;
        if (parent == null) {
            parent = new Node(middle);
            parent.connect(0, left);
            parent.connect(1, right);
        }
        else {
            int index = parent.insert(middle);
            parent.insert_child(index + 1, right);
        }

        if (!is_leaf()) {
            Node child1 = disConnect(2);
            Node child2 = disConnect(3);
            right.connect(0, child1);
            right.connect(1, child2);
        }
        return parent;
    }
}