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leetcode/problem/word-frequency.html

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+<p>Write a bash script to calculate the frequency of each word in a text file <code>words.txt</code>.</p>
+
+<p>For simplicity sake, you may assume:</p>
+
+<ul>
+	<li><code>words.txt</code> contains only lowercase characters and space <code>&#39; &#39;</code> characters.</li>
+	<li>Each word must consist of lowercase characters only.</li>
+	<li>Words are separated by one or more whitespace characters.</li>
+</ul>
+
+<p><strong>Example:</strong></p>
+
+<p>Assume that <code>words.txt</code> has the following content:</p>
+
+<pre>
+the day is sunny the the
+the sunny is is
+</pre>
+
+<p>Your script should output the following, sorted by descending frequency:</p>
+
+<pre>
+the 4
+is 3
+sunny 2
+day 1
+</pre>
+
+<p><b>Note:</b></p>
+
+<ul>
+	<li>Don&#39;t worry about handling ties, it is guaranteed that each word&#39;s frequency count is unique.</li>
+	<li>Could you write it in one-line using <a href="http://tldp.org/HOWTO/Bash-Prog-Intro-HOWTO-4.html">Unix pipes</a>?</li>
+</ul>