刷题-力扣-面试题 16.02. 单词频率
题目链接
来源:力扣(LeetCode)
链接:https://leetcode-cn.com/problems/words-frequency-lcci
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题目描述
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
提示:
- book[i]中只包含小写字母
- 1 <= book.length <= 100000
- 1 <= book[i].length <= 10
- get函数的调用次数不会超过100000
题目分析
- 根据题目描述,计算词频
- 将输入的单词存储到hash表中,键为单词,值为出现的次数
代码
class WordsFrequency {
private:
std::unordered_map<std::string, int> map;
public:
WordsFrequency(vector<string>& book) {
for (auto word : book) { this->map[word] += 1; }
return;
}
int get(string word) {
return this->map[word];
}
};
/**
* Your WordsFrequency object will be instantiated and called as such:
* WordsFrequency* obj = new WordsFrequency(book);
* int param_1 = obj->get(word);
*/