Create longest-palindrome.cpp

Author: kamyu104

C++/longest-palindrome.cpp

@@ -0,0 +1,13 @@
+// Time:  O(n)
+// Space: O(1)
+
+class Solution {
+public:
+    int longestPalindrome(string s) {
+        int odds = 0;
+        for (auto c = 'A'; c <= 'z'; ++c) {
+            odds += count(s.cbegin(), s.cend(), c) & 1;
+        }
+        return s.length() - odds + (odds > 0);
+    }
+};