[Leetcode]Longest Palindrome

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.

1. 解題思路

咱們發現結果其實就是字符的偶數個數+是否有單一的字符，若是有就加1(把單一字符放在迴文中間)，若是沒有就加0；
字母區分大小寫，int[] map=new int['z'-'A'+1];
2.代碼

public class Solution {
    public int longestPalindrome(String s) {
        if(s.length()==0||s==null) return 0;
        int[] map=new int['z'-'A'+1];
        int count=0;
        int hasOdd=0;
        for(int i=0;i<s.length();i++){
            map[s.charAt(i)-'A']++;
        }
        for(char c='A';c<='z';c++){
            if((map[c-'A'] & 1)==1){
                hasOdd=1;
                count+=(map[c-'A']-1);
            }
            else 
                count+=map[c-'A'];
        }
        return count+hasOdd;
    }
}