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409. Longest Palindrome

Difficulty Topics

Description

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 here.

 

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

longest-palindrome.py
class Solution:
    def longestPalindrome(self, s: str) -> int:
        odd = set()

        for char in s:
            if char in odd:
                odd.remove(char)
            else:
                odd.add(char)

        return len(s) - len(odd) + int(len(odd) > 0)