題目
Given a string which consists of lowercase or uppercase letters, find the length of the longest palindromes that can be built with those letters.
This is case sensitive, for example "Aa" is not considered a palindrome here.
Note:
Assume the length of given string will not exceed 1,010.
Example:
Input:
"abccccdd"
Output:
7
Explanation:
One longest palindrome that can be built is "dccaccd", whose length is 7.
難度
Easy
方法
先統(tǒng)計每個字符出現的次數，對于出現偶數次的字符，能全部用于組成回文。對于出現基數次n的字符货岭，能用n-1個字符。如果有出現基數次的字符，最后能單獨用一個該字符
python代碼
class Solution(object):
def longestPalindrome(self, s):
"""
:type s: str
:rtype: int
"""
counter = {}
for c in s:
if counter.has_key(c):
counter[c] += 1
else:
counter[c] = 1
palindrome_length = 0
single = False
for key in counter:
if counter[key] % 2 == 0:
palindrome_length += counter[key]
else:
palindrome_length += counter[key] - 1
single = True
if single:
palindrome_length += 1
return palindrome_length
assert Solution().longestPalindrome("abccccdd") == 7
