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開學之前....系列 第 11

Day12 - 409. Longest Palindrome

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今日題目:409. Longest Palindrome

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

解題技巧

1. str.count(sub, start= 0,end=len(string))

str = 'banana pie banana'
str.count('a',2)
->5

2. collections.Counter()

str2 = 'gallahad'

  • c = Counter(str2)
    ->Counter({'a': 3, 'n': 2, 'b': 1, 's': 1})

  • Counter.items()->['a': 3, 'n': 2, 'b': 1, 's': 1]

  • Counter.values()->[3,2,1,1]

  • Counter.keys()->['a','n','b','s']

My solution

class Solution:
    def longestPalindrome(self, s: str) -> int:
        n = len(s)
        c = collections.Counter(s)
    
        ans = 0
        odd = 0
        
        for v in c.values():
            ans += int(v/2)*2

            if ans%2 ==0 and v%2==1:
                ans +=1
        return ans

Result

https://ithelp.ithome.com.tw/upload/images/20210927/20140843wb7Emx2ypf.png


上一篇
Day11-415. Add Strings
下一篇
Day13-290. Word Pattern
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