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409. Longest Palindrome

时间:2018-11-16 17:43:50      阅读:116      评论:0      收藏:0      [点我收藏+]

标签:can   ati   which   body   order   and   letters   status   turn   

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

 

409. Longest Palindrome

标签:can   ati   which   body   order   and   letters   status   turn   

原文地址:https://www.cnblogs.com/ruruozhenhao/p/9969751.html

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