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Tested Python solution for LeetCode 409 with 13 pytest cases. Generate a practice environment with lcpy.
lcpy gen -n 409 # by problem number
lcpy gen -s longest_palindrome # by problem name
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.
Input: s = "abccccdd"
Output: 7
Input: s = "a"
Output: 1
1 <= s.length <= 2000s consists of lowercase and/or uppercase English letters only.class Solution:
# Time: O(n)
# Space: O(1)
def longest_palindrome(self, s: str) -> int:
char_count: dict[str, int] = {}
for char in s:
char_count[char] = char_count.get(char, 0) + 1
length = 0
has_odd = False
for count in char_count.values():
length += count // 2 * 2
if count % 2 == 1:
has_odd = True
return length + (1 if has_odd else 0)
| Time | Space |
|---|---|
| O(n) | O(1) |