import java.util.ArrayList;
public class BST, 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 BST(){
root = null;
size = 0;
}
public int getSize(){
return size;
}
public boolean isEmpty(){
return size == 0;
}
// å‘二分æœç´¢æ ‘ä¸æ·»åŠ æ–°çš„å…ƒç´ (key, value)
public void add(K key, V value){
root = add(root, key, value);
}
// å‘以nodeä¸ºæ ¹çš„äºŒåˆ†æœç´¢æ ‘ä¸æ’å…¥å…ƒç´ (key, value)，递归算法
// 返回æ’入新节点åŽäºŒåˆ†æœç´¢æ ‘çš„æ ¹
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nodeä¸ºæ ¹èŠ‚ç‚¹çš„äºŒåˆ†æœç´¢æ ‘ä¸ï¼Œkey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);
}
public boolean contains(K key){
return getNode(root, key) != null;
}
public V get(K key){
Node node = getNode(root, key);
return node == null ? null : node.value;
}
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nodeä¸ºæ ¹çš„äºŒåˆ†æœç´¢æ ‘的最å°å€¼æ‰€åœ¨çš„节点
private Node minimum(Node node){
if(node.left == null)
return node;
return minimum(node.left);
}
// åˆ é™¤æŽ‰ä»¥nodeä¸ºæ ¹çš„äºŒåˆ†æœç´¢æ ‘ä¸çš„最å°èŠ‚点
// è¿”å›žåˆ é™¤èŠ‚ç‚¹åŽæ–°çš„二分æœç´¢æ ‘çš„æ ¹
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æœç´¢æ ‘ä¸åˆ 除键为key的节点
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
// å¾…åˆ é™¤èŠ‚ç‚¹å·¦åæ ‘ä¸ºç©ºçš„æƒ…å†µ
if(node.left == null){
Node rightNode = node.right;
node.right = null;
size --;
return rightNode;
}
// å¾…åˆ é™¤èŠ‚ç‚¹å³åæ ‘ä¸ºç©ºçš„æƒ…å†µ
if(node.right == null){
Node leftNode = node.left;
node.left = null;
size --;
return leftNode;
}
// å¾…åˆ é™¤èŠ‚ç‚¹å·¦å³åæ ‘å‡ä¸ä¸ºç©ºçš„情况
// æ‰¾åˆ°æ¯”å¾…åˆ é™¤èŠ‚ç‚¹å¤§çš„æœ€å°èŠ‚点, å³å¾…åˆ é™¤èŠ‚ç‚¹å³åæ ‘çš„æœ€å°èŠ‚点
// ç”¨è¿™ä¸ªèŠ‚ç‚¹é¡¶æ›¿å¾…åˆ é™¤èŠ‚ç‚¹çš„ä½ç½®
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 words = new ArrayList<>();
if(FileOperation.readFile("pride-and-prejudice.txt", words)) {
System.out.println("Total words: " + words.size());
BST map = new BST<>();
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();
}
}