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

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

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

<p>A <strong>palindrome</strong> is a string that reads the same forward and backward.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> words = [&quot;lc&quot;,&quot;cl&quot;,&quot;gg&quot;]
<strong>Output:</strong> 6
<strong>Explanation:</strong> 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>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> words = [&quot;ab&quot;,&quot;ty&quot;,&quot;yt&quot;,&quot;lc&quot;,&quot;cl&quot;,&quot;ab&quot;]
<strong>Output:</strong> 8
<strong>Explanation:</strong> 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>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> words = [&quot;cc&quot;,&quot;ll&quot;,&quot;xx&quot;]
<strong>Output:</strong> 2
<strong>Explanation:</strong> 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>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= words.length &lt;= 10<sup>5</sup></code></li>
	<li><code>words[i].length == 2</code></li>
	<li><code>words[i]</code> consists of lowercase English letters.</li>
</ul>

class Solution {
public:
    int longestPalindrome(vector<string>& words) {

        map<string, int> freq;
        int length = 0;
        bool central_palindrome = false;

        // Count the frequency of each word
        for (const auto& word : words) {
            freq[word]++;
        }


        for (auto it : freq) {
            string word = it.first;
            int count = it.second;
            string rev_word = string(word.rbegin(), word.rend());
            cout<<word<<" "<<rev_word<<" "<<count<<"\n";

            if (word == rev_word) {
                // If the word is a self-palindrome (like "gg")
                int pairs = count / 2;
                length += pairs * 4; // Each pair contributes 4 characters
                if (count % 2 == 1) {
                    central_palindrome = true;  // Can use one self-palindrome as the center
                }
            } else if (freq[rev_word] > 0) {
                // If the word has a reverse counterpart (like "lc" and "cl")
                int pairs = min(count, freq[rev_word]);
                length += pairs * 4; // Each pair contributes 4 characters
                freq[rev_word] = 0;  // Set reverse word count to 0 to avoid double counting
                freq[word] = 0;
            }
        }

        // If we have a self-palindrome for the center, add 2 characters to the length
        if (central_palindrome) {
            length += 2;
        }

        return length;
    }
};
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