JavaArithmetic/src/datastructure/map/BSTMap.java at master · Edwardlinge/JavaArithmetic · GitHub

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package datastructure.map;

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;

left = null;

right = null;

}

private Node root;

private int size;

public BSTMap(){

root = null;

size = 0;

}

@Override

public int getSize(){

return size;

}

@Override

public boolean isEmpty(){

return size == 0;

}

// 向二分搜索树中添加新的元素(key, value)

@Override

public void add(K key, V value){

root = add(root, key, value);

}

// 向以node为根的二分搜索树中插入元素(key, value)，递归算法

// 返回插入新节点后二分搜索树的根

private Node add(Node node, K key, V value){

if(node == null){

size ++;

return new Node(key, value);

}

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 // key.compareTo(node.key) == 0

node.value = value;

return node;

}

// 返回以node为根节点的二分搜索树中，key所在的节点

private Node getNode(Node node, K key){

if(node == null)

return null;

if(key.equals(node.key))

return node;

else if(key.compareTo(node.key) < 0)

return getNode(node.left, key);

else // if(key.compareTo(node.key) > 0)

return getNode(node.right, key);

}

@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 newValue){

Node node = getNode(root, key);

if(node == null)

throw new IllegalArgumentException(key + " doesn't exist!");

node.value = newValue;

}

// 返回以node为根的二分搜索树的最小值所在的节点

private Node minimum(Node node){

if(node.left == null)

return node;

return minimum(node.left);

}

// 删除掉以node为根的二分搜索树中的最小节点

// 返回删除节点后新的二分搜索树的根

private Node removeMin(Node node){

if(node.left == null){

Node rightNode = node.right;

node.right = null;

size --;

return rightNode;

}

node.left = removeMin(node.left);

return node;

}

// 从二分搜索树中删除键为key的节点

@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){

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{ // key.compareTo(node.key) == 0

// 待删除节点左子树为空的情况

if(node.left == null){

Node rightNode = node.right;

node.right = null;

size --;

return rightNode;

}

// 待删除节点右子树为空的情况

if(node.right == null){

Node leftNode = node.left;

node.left = null;

size --;

return leftNode;

}

// 待删除节点左右子树均不为空的情况

// 找到比待删除节点大的最小节点, 即待删除节点右子树的最小节点

// 用这个节点顶替待删除节点的位置

Node successor = minimum(node.right);

successor.right = removeMin(node.right);

successor.left = node.left;

node.left = node.right = null;

return successor;

}

public static void main(String[] args){

System.out.println("Pride and Prejudice");

ArrayList<String> words = new ArrayList<>();

if(FileOperation.readFile("pride-and-prejudice.txt", words)) {

System.out.println("Total words: " + words.size());

BSTMap<String, Integer> map = new BSTMap<>();

for (String word : words) {

if (map.contains(word))

map.set(word, map.get(word) + 1);

else

map.add(word, 1);

}

System.out.println("Total different words: " + map.getSize());

System.out.println("Frequency of PRIDE: " + map.get("pride"));

System.out.println("Frequency of PREJUDICE: " + map.get("prejudice"));

}

System.out.println();

}

JavaArithmetic/src/datastructure/map/BSTMap.java at master · Edwardlinge/JavaArithmetic · GitHub

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