Moderate 查单词 @CareerCup

简单题，如果是只查询一次，则用时O(n)

如果要多次查询，则用一个Hashtable存储已查过的词

package Moderate;

import java.util.Hashtable;

import CtCILibrary.AssortedMethods;

/**
 * Design a method to find the frequency of occurrences of any given word in a
 * book.
 * 
 * 译文：
 * 
 * 设计一个函数，找到给定单词在一本书中的出现次数。
 * 
 */
public class S17_9 {

	// 预处理，事先处理好，放在一个Hashtable里
	public static Hashtable
  
    setupDictionary(String[] book) {
		Hashtable
   
     table = new Hashtable
    
     (); for (String word : book) { word = word.toLowerCase(); if (word.trim() != "") { if (!table.containsKey(word)) { table.put(word, 0); } table.put(word, table.get(word) + 1); } } return table; } public static int getFrequency(Hashtable
     
       table, String word) { if (table == null || word == null) { return -1; } word = word.toLowerCase(); if (table.containsKey(word)) { return table.get(word); } return 0; } public static void main(String[] args) { String[] wordlist = AssortedMethods.getLongTextBlobAsStringList(); Hashtable
      
        dictionary = setupDictionary(wordlist); String[] words = { "the", "Lara", "and", "outcropping", "career", "it" }; for (String word : words) { System.out.println(word + ": " + getFrequency(dictionary, word)); } } }