Longest Palindrome
<p>Given a string <code>s</code> which consists of lowercase or uppercase letters, return the length of the <strong>longest <span data-keyword="palindrome-string">palindrome</span></strong>&nbsp;that can be built with those letters.</p>

<p>Letters are <strong>case sensitive</strong>, for example, <code>&quot;Aa&quot;</code> is not considered a palindrome.</p>

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

<pre>
<strong>Input:</strong> s = &quot;abccccdd&quot;
<strong>Output:</strong> 7
<strong>Explanation:</strong> One longest palindrome that can be built is &quot;dccaccd&quot;, whose length is 7.
</pre>

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

<pre>
<strong>Input:</strong> s = &quot;a&quot;
<strong>Output:</strong> 1
<strong>Explanation:</strong> The longest palindrome that can be built is &quot;a&quot;, whose length is 1.
</pre>

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

<ul>
	<li><code>1 &lt;= s.length &lt;= 2000</code></li>
	<li><code>s</code> consists of lowercase <strong>and/or</strong> uppercase English&nbsp;letters only.</li>
</ul>
Greedy; Hash Table; String
function longestPalindrome(s: string): number {
    const cnt: Record<string, number> = {};
    for (const c of s) {
        cnt[c] = (cnt[c] || 0) + 1;
    }
    let ans = Object.values(cnt).reduce((acc, v) => acc + Math.floor(v / 2) * 2, 0);
    ans += ans < s.length ? 1 : 0;
    return ans;
}
