longest-palindrome-by-concatenating-two-letter-words

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Algorithms

You are given an array of strings <code>words</code>. Each element of <code>words</code> consists of two lowercase English letters.

Create the longest possible palindrome by selecting some elements from <code>words</code> and concatenating them in any order. Each element can be selected at most once.

Return the length of the longest palindrome that you can create. If it is impossible to create any palindrome, return <code>0</code>.

A palindrome is a string that reads the same forward and backward.

&nbsp;
Example 1:

<pre>
Input: words = [&quot;lc&quot;,&quot;cl&quot;,&quot;gg&quot;]
Output: 6
Explanation: One longest palindrome is &quot;lc&quot; + &quot;gg&quot; + &quot;cl&quot; = &quot;lcggcl&quot;, of length 6.
Note that &quot;clgglc&quot; is another longest palindrome that can be created.
</pre>

Example 2:

<pre>
Input: words = [&quot;ab&quot;,&quot;ty&quot;,&quot;yt&quot;,&quot;lc&quot;,&quot;cl&quot;,&quot;ab&quot;]
Output: 8
Explanation: One longest palindrome is &quot;ty&quot; + &quot;lc&quot; + &quot;cl&quot; + &quot;yt&quot; = &quot;tylcclyt&quot;, of length 8.
Note that &quot;lcyttycl&quot; is another longest palindrome that can be created.
</pre>

Example 3:

<pre>
Input: words = [&quot;cc&quot;,&quot;ll&quot;,&quot;xx&quot;]
Output: 2
Explanation: One longest palindrome is &quot;cc&quot;, of length 2.
Note that &quot;ll&quot; is another longest palindrome that can be created, and so is &quot;xx&quot;.
</pre>

&nbsp;
Constraints:

<ul>
	<li><code>1 &lt;= words.length &lt;= 105</code></li>
	<li><code>words[i].length == 2</code></li>
	<li><code>words[i]</code> consists of lowercase English letters.</li>
</ul>

longestPalindrome

Longest Palindrome by Concatenating Two Letter Words

Palindrome Pairs

palindrome-pairs

回文对

Longest Palindrome

longest-palindrome

最长回文串

Greedy

Array

Hash Table

String

Counting

给你一个字符串数组&nbsp;<code>words</code>&nbsp;。<code>words</code>&nbsp;中每个元素都是一个包含 两个&nbsp;小写英文字母的单词。

请你从 <code>words</code>&nbsp;中选择一些元素并按 任意顺序&nbsp;连接它们，并得到一个 尽可能长的回文串&nbsp;。每个元素 至多&nbsp;只能使用一次。

请你返回你能得到的最长回文串的 长度&nbsp;。如果没办法得到任何一个回文串，请你返回 <code>0</code>&nbsp;。

回文串&nbsp;指的是从前往后和从后往前读一样的字符串。

&nbsp;

示例 1：

<pre>输入：words = ["lc","cl","gg"]
输出：6
解释：一个最长的回文串为 "lc" + "gg" + "cl" = "lcggcl" ，长度为 6 。
"clgglc" 是另一个可以得到的最长回文串。
</pre>

示例 2：

<pre>输入：words = ["ab","ty","yt","lc","cl","ab"]
输出：8
解释：最长回文串是 "ty" + "lc" + "cl" + "yt" = "tylcclyt" ，长度为 8 。
"lcyttycl" 是另一个可以得到的最长回文串。
</pre>

示例 3：

<pre>输入：words = ["cc","ll","xx"]
输出：2
解释：最长回文串是 "cc" ，长度为 2 。
"ll" 是另一个可以得到的最长回文串。"xx" 也是。</pre>

&nbsp;

提示：

<ul>
	<li><code>1 &lt;= words.length &lt;= 105</code></li>
	<li><code>words[i].length == 2</code></li>
	<li><code>words[i]</code>&nbsp;仅包含小写英文字母。</li>
</ul>