#yyds干货盘点# LeetCode程序员面试金典：单词频率

Posted 2023-02-22

题目：

设计一个方法，找出任意指定单词在一本书中的出现频率。

你的实现应该支持如下操作：

WordsFrequency(book)构造函数，参数为字符串数组构成的一本书

get(word)查询指定单词在书中出现的频率

示例：

WordsFrequency wordsFrequency = new WordsFrequency("i", "have", "an", "apple", "he", "have", "a", "pen");

wordsFrequency.get("you"); //返回0，"you"没有出现过

wordsFrequency.get("have"); //返回2，"have"出现2次

wordsFrequency.get("an"); //返回1

wordsFrequency.get("apple"); //返回1

wordsFrequency.get("pen"); //返回1

代码实现：

class WordsFrequency 
    private HashMap<String, Integer> map = new HashMap<>();

    public WordsFrequency(String[] book) 
        for (String word : book) 
            map.put(word, map.getOrDefault(word, 0) + 1);
        
    

    public int get(String word) 
        return map.getOrDefault(word, 0);