Sync LeetCode submission Runtime - 42 ms (21.17%), Memory - 16.5 MB (50.23%)

Author: jimit105

0409-longest-palindrome/README.md

@@ -0,0 +1,28 @@
+<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>

0409-longest-palindrome/solution.py

@@ -0,0 +1,31 @@
+# Approach 1: Greedy Way (Hash Table)
+
+# Time: O(n)
+
+class Solution:
+    def longestPalindrome(self, s: str) -> int:
+        freq = {}
+
+        for c in s:
+            freq[c] = freq.get(c, 0) + 1
+
+        res = 0
+        has_odd_freq = False
+
+        for f in freq.values():
+            if (f % 2) == 0:
+                res += f
+
+            else:
+                # If the frequency is odd, one occurrence of the
+                # character will remain without a match
+                res += f - 1
+                has_odd_freq = True
+
+        # If has_odd_frequency is true, we have at least one unmatched
+        # character to make the center of an odd length palindrome.
+        if has_odd_freq:
+            return res + 1
+
+        return res
+