409. Longest Palindrome

Problem Link

Description

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Given a string s which consists of lowercase or uppercase letters, return the length of the longest palindrome that can be built with those letters.

Letters are case sensitive, for example, "Aa" is not considered a palindrome.

 

Example 1:

Input: s = "abccccdd"
Output: 7
Explanation: One longest palindrome that can be built is "dccaccd", whose length is 7.

Example 2:

Input: s = "a"
Output: 1
Explanation: The longest palindrome that can be built is "a", whose length is 1.

 

Constraints:

• 1 <= s.length <= 2000
• s consists of lowercase and/or uppercase English letters only.

Solution

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Python3

class Solution:
    def longestPalindrome(self, s: str) -> int:
        hasOdd = False
        counter = Counter(s)
        res = 0
 
        for v in counter.values():
            if v % 2 == 0:
                res += v
            else:
                res += v - 1
                hasOdd = True
        
        return res + int(hasOdd)