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  • 409. Longest Palindrome

    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.
    
     Approach #1: C++.
    class Solution {
    public:
        int longestPalindrome(string s) {
            unordered_map<char, int> mp;
            int nums = 0;
            bool flag = false;
            for (int i = 0; i < s.length(); ++i) 
                mp[s[i]]++;
            for (auto it = mp.begin(); it != mp.end(); ++it) {
                nums += it->second/2 * 2;
                if (it->second % 2 != 0 && !flag) 
                    flag = true;
            }
            if (flag) nums++;
            return nums;
        }
    private:
        static bool cmp(int a, int b) {
            return a >= b;
        }
    };
    

      

    Approach #2: Java.

    class Solution {
        public int longestPalindrome(String s) {
            int[] count = new int[128];
            for (char c : s.toCharArray()) 
                count[c]++;
            int ans = 0;
            for (int v : count) {
                ans += v / 2 * 2;
                if (ans % 2 == 0 && v % 2 == 1)
                    ans++;
            }
            return ans;
        }
    }
    

      

    Approach #3: Python.

    class Solution(object):
        def longestPalindrome(self, s):
            """
            :type s: str
            :rtype: int
            """
            ans = 0
            for v in collections.Counter(s).itervalues():
                ans += v / 2 * 2
                if ans % 2 == 0 and v % 2 == 1:
                    ans += 1
                
            return ans
    

      

    Time SubmittedStatusRuntimeLanguage
    a few seconds ago Accepted 44 ms python
    2 minutes ago Accepted 5 ms java
    5 minutes ago Accepted 8 ms cpp
    永远渴望,大智若愚(stay hungry, stay foolish)
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  • 原文地址:https://www.cnblogs.com/h-hkai/p/9969751.html
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