国外版

算法题（国外版）/maximum-length-of-a-concatenated-string-with-unique-characters.html

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+<p>You are given an array of strings <code>arr</code>. A string <code>s</code> is formed by the <strong>concatenation</strong> of a <strong>subsequence</strong> of <code>arr</code> that has <strong>unique characters</strong>.</p>
+
+<p>Return <em>the <strong>maximum</strong> possible length</em> of <code>s</code>.</p>
+
+<p>A <strong>subsequence</strong> is an array that can be derived from another array by deleting some or no elements without changing the order of the remaining elements.</p>
+
+<p>&nbsp;</p>
+<p><strong>Example 1:</strong></p>
+
+<pre>
+<strong>Input:</strong> arr = [&quot;un&quot;,&quot;iq&quot;,&quot;ue&quot;]
+<strong>Output:</strong> 4
+<strong>Explanation:</strong> All the valid concatenations are:
+- &quot;&quot;
+- &quot;un&quot;
+- &quot;iq&quot;
+- &quot;ue&quot;
+- &quot;uniq&quot; (&quot;un&quot; + &quot;iq&quot;)
+- &quot;ique&quot; (&quot;iq&quot; + &quot;ue&quot;)
+Maximum length is 4.
+</pre>
+
+<p><strong>Example 2:</strong></p>
+
+<pre>
+<strong>Input:</strong> arr = [&quot;cha&quot;,&quot;r&quot;,&quot;act&quot;,&quot;ers&quot;]
+<strong>Output:</strong> 6
+<strong>Explanation:</strong> Possible longest valid concatenations are &quot;chaers&quot; (&quot;cha&quot; + &quot;ers&quot;) and &quot;acters&quot; (&quot;act&quot; + &quot;ers&quot;).
+</pre>
+
+<p><strong>Example 3:</strong></p>
+
+<pre>
+<strong>Input:</strong> arr = [&quot;abcdefghijklmnopqrstuvwxyz&quot;]
+<strong>Output:</strong> 26
+<strong>Explanation:</strong> The only string in arr has all 26 characters.
+</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>1 &lt;= arr.length &lt;= 16</code></li>
+	<li><code>1 &lt;= arr[i].length &lt;= 26</code></li>
+	<li><code>arr[i]</code> contains only lowercase English letters.</li>
+</ul>