409.Longest Palindrome
===
###### tags: `Easy`,`String`,`Greedy`,`Hash Table`
[409. Longest Palindrome](https://leetcode.com/problems/longest-palindrome/)

### 題目描述
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.

### 範例

Input: s = "abccccdd"
Output: 7
Explanation: One longest palindrome that can be built is "dccaccd", whose length is 7.

Input: s = "a"
Output: 1
Explanation: The longest palindrome that can be built is "a", whose length is 1.

**Constraints**:
* 1 <= s.length <= 2000
* s consists of lowercase and/or uppercase English letters only.

### 解答
#### Python

class Solution:
    def longestPalindrome(self, s: str) -> int:
        if len(s) == 1: return 1
        
        ht = defaultdict(int)
        for ch in s:
            ht[ch] += 1
            
        res = 0
        for key, val in ht.items():
            res += val // 2 * 2
            
        for key, val in ht.items():
            if ht[key] % 2 == 1:
                res += 1
                break;
                
        return res

> [name=Kobe] [time= Nov 23, 2022]

#### Javascript

function longestPalindrome(s) {
  const count = [];
  for (const char of s) {
    if (count[char]) {
      count[char]++;
    } else {
      count[char] = 1;
    }
  }

  let result = 0;
  let hasOdd = false;
  for (const char in count) {
    if (count[char] % 2 === 0) {
      result += count[char];
    } else {
      result += count[char] - 1; // 大於2以上的奇數
      hasOdd = true; // 剩下的可以當中間項
    }
  }

  return hasOdd ? result + 1 : result;
}

> [name=Marsgoat] [time= Nov 29, 2022]

### Reference

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