most-common-word.md

<p>Given a paragraph&nbsp;and a list of banned words, return the most frequent word that is not in the list of banned words.&nbsp; It is guaranteed there is at least one word that isn&#39;t banned, and that the answer is unique.</p>

<p>Words in the list of banned words are given in lowercase, and free of punctuation.&nbsp; Words in the paragraph are not case sensitive.&nbsp; The answer is in lowercase.</p>

<p>&nbsp;</p>

<p><strong>Example:</strong></p>

<pre>
<strong>Input:</strong> 
paragraph = &quot;Bob hit a ball, the hit BALL flew far after it was hit.&quot;
banned = [&quot;hit&quot;]
<strong>Output:</strong> &quot;ball&quot;
<strong>Explanation:</strong> 
&quot;hit&quot; occurs 3 times, but it is a banned word.
&quot;ball&quot; occurs twice (and no other word does), so it is the most frequent non-banned word in the paragraph. 
Note that words in the paragraph are not case sensitive,
that punctuation is ignored (even if adjacent to words, such as &quot;ball,&quot;), 
and that &quot;hit&quot; isn&#39;t the answer even though it occurs more because it is banned.
</pre>

<p>&nbsp;</p>

<p><strong>Note: </strong></p>

<ul>
	<li><code>1 &lt;= paragraph.length &lt;= 1000</code>.</li>
	<li><code>0 &lt;= banned.length &lt;= 100</code>.</li>
	<li><code>1 &lt;= banned[i].length &lt;= 10</code>.</li>
	<li>The answer is unique, and written in lowercase (even if its occurrences in <code>paragraph</code>&nbsp;may have&nbsp;uppercase symbols, and even if it is a proper noun.)</li>
	<li><code>paragraph</code> only consists of letters, spaces, or the punctuation symbols <code>!?&#39;,;.</code></li>
	<li>There are no hyphens or hyphenated words.</li>
	<li>Words only consist of letters, never apostrophes or other punctuation symbols.</li>
</ul>