16.基於二分搜索樹實現Map

package com.cl.map;

import com.cl.set.FileOperation;

import java.util.ArrayList;

public class BSTMap<K extends Comparable<K>,V> implements Map<K,V> {

    private class Node{
        public K key;
        public V value;
        public Node left,right;
        public Node(K key,V value){
            this.key=key;
            this.value = value;
            this.left = this.right=null;
        }
    }

    private Node root;
    private int size;
    public BSTMap() {
        root = null;
        size = 0;
    }

    private Node getNode(Node node,K key){
        if(node==null){
            return null;
        }
        if(key.compareTo(node.key)==0){
            return node;
        }else if(key.compareTo(node.key)<0){
            return getNode(node.left,key);
        }else{
            return getNode(node.right,key);
        }
    }
    @Override
    public void add(K key,V value){
        root =  add(root,key,value);
    }

    /**遞歸
     * 向以node爲根節點的樹插入元素
     * @return:返回插入新結點後二分搜索樹的根
     */
    private Node add(Node node,K key,V value){
        if(node==null){
            size++;
            return new Node(key,value);
        }
        //遞歸調用
        if(key.compareTo(node.key)<0)
            node.left=add(node.left,key,value);
        else if(key.compareTo(node.key)>0){
            node.right=add(node.right,key,value);
        }else{//重新設值
            node.value=value;
        }
        return node;
    }

    /**
     * 找以node爲根的樹的最小結點
     * @param node
     * @return 返回最小的結點
     */
    private Node minmum(Node node) {
        if(node.left==null){
            return node;
        }
        return minmum(node.left);
    }

    /**
     * 刪除以node爲根節點的樹的最小節點
     * @param node
     * @return：返回刪除後的子樹的根
     */
    private Node removeMin(Node node) {
        if(node.left==null){//找到最小值的結點
            Node rigthNode = node.right;//null或者非空
            node.right=null;
            size--;
            return rigthNode;
        }
        node.left = removeMin(node.left);
        return node;

    }

    @Override
    public V remove(K key) {
        Node node = getNode(root,key);
        if(node!=null){
            root = remove(root,key);
            return node.value;
        }
        return null;
    }

    private Node remove(Node node, K key) {
        //沒找到
        if(node==null){
            return null;
        }

        if(key.compareTo(node.key)<0){
            node.left = remove(node.left,key);
            return node;
        }else if(key.compareTo(node.key)>0){
            node.right=remove(node.right,key);
            return node;
        }else {//e==node.e,找到刪除的結點
            //左子樹空
            if(node.left==null){
                Node rightNoe = node.right;
                node.right=null;
                size--;
                return rightNoe;
            }else if(node.right==null){//右子樹空
                Node leftNode = node.left;
                node.left=null;
                size--;
                return leftNode;
            }else{//都不空
                //找到比待刪除結點的右子樹中最小的結點
                //用這個結點刪除待刪除的結點
                Node successor = minmum(node.right);
                //removeMin裏有一次size--
                successor.right = removeMin(node.right);
                successor.left = node.left;
                node.left=node.right=null;
                return successor;
            }
        }
    }

    @Override
    public boolean contains(K key) {
        return getNode(root,key)!=null;
    }

    @Override
    public V get(K key) {
        Node node = getNode(root,key);
        return node == null?null:node.value;
    }

    @Override
    public void set(K key, V value) {
        Node node = getNode(root,key);
        if(node==null){
            throw new IllegalArgumentException(node+" not exist");
        }
        node.value=value;
    }

    @Override
    public int getSise() {
        return size;
    }

    @Override
    public boolean isEmpty() {
        return size==0;
    }

    public static void main(String[] args) {
        String filename = "pride-and-prejudice.txt";
        ArrayList<String> words1 = new ArrayList<>();
        FileOperation.readFile("src/"+filename,words1);
        System.out.println("Total words:"+words1.size());
        BSTMap<String,Integer> map = new BSTMap<>();
        for (String word:words1) {
            if(map.contains(word)){
                map.set(word,map.get(word)+1);
            }
            else map.add(word,1);
        }
        System.out.println("Total diffrent words:"+map.getSise());
        System.out.println("Frenquncy of pride:"+map.get("pride"));

    }
}