words-frequency-lcci

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LCCI

Design a method to find the frequency of occurrences of any given word in a book. What if we were running this algorithm multiple times?

You should implement following methods:

<ul>
	<li><code>WordsFrequency(book)</code> constructor, parameter is a array of strings, representing the book.</li>
	<li><code>get(word)</code>&nbsp;get the frequency of <code>word</code> in the book.&nbsp;</li>
</ul>

Example: 

<pre>
WordsFrequency wordsFrequency = new WordsFrequency({&quot;i&quot;, &quot;have&quot;, &quot;an&quot;, &quot;apple&quot;, &quot;he&quot;, &quot;have&quot;, &quot;a&quot;, &quot;pen&quot;});
wordsFrequency.get(&quot;you&quot;); //returns 0，&quot;you&quot; is not in the book
wordsFrequency.get(&quot;have&quot;); //returns 2，&quot;have&quot; occurs twice in the book
wordsFrequency.get(&quot;an&quot;); //returns 1
wordsFrequency.get(&quot;apple&quot;); //returns 1
wordsFrequency.get(&quot;pen&quot;); //returns 1
</pre>

Note: 

<ul>
	<li><code>There are only lowercase letters in book[i].</code></li>
	<li><code>1 &lt;= book.length &lt;= 100000</code></li>
	<li><code>1 &lt;= book[i].length &lt;= 10</code></li>
	<li><code>get</code>&nbsp;function will not be called more than&nbsp;100000 times.</li>
</ul>

Words Frequency LCCI

Design

Trie

Array

Hash Table

String

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：

<ul>
	<li><code>WordsFrequency(book)</code>构造函数，参数为字符串数组构成的一本书</li>
	<li><code>get(word)</code>查询指定单词在书中出现的频率</li>
</ul>

示例：

<pre>WordsFrequency wordsFrequency = new WordsFrequency({&quot;i&quot;, &quot;have&quot;, &quot;an&quot;, &quot;apple&quot;, &quot;he&quot;, &quot;have&quot;, &quot;a&quot;, &quot;pen&quot;});
wordsFrequency.get(&quot;you&quot;); //返回0，&quot;you&quot;没有出现过
wordsFrequency.get(&quot;have&quot;); //返回2，&quot;have&quot;出现2次
wordsFrequency.get(&quot;an&quot;); //返回1
wordsFrequency.get(&quot;apple&quot;); //返回1
wordsFrequency.get(&quot;pen&quot;); //返回1
</pre>

提示：

<ul>
	<li><code>book[i]</code>中只包含小写字母</li>
	<li><code>1 &lt;= book.length &lt;= 100000</code></li>
	<li><code>1 &lt;= book[i].length &lt;= 10</code></li>
	<li><code>get</code>函数的调用次数不会超过100000</li>
</ul>