# 409. Longest Palindrome

Easy
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
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.

### 解題

Runtime: 0 ms, faster than 100.00%
Memory Usage: 2 MB, less than 83.31%
func longestPalindrome(s string) int {
counter := make([]int, 52)
for _, val := range s {
if val>='A' && val<='Z' {
counter[val-'A'+26]++
} else if val>='a' && val<='z' {
counter[val-'a']++
}
}
odd := 0
sum := 0
for _, val := range counter {
if val%2 == 0 {
sum += val
} else {
sum += val-1
odd ++
}
}
if odd>0 { return sum+1 }
return sum
}