# 0266. Palindrome Permutation
###### tags: `Leetcode` `Easy` `FaceBook` `Palindrome`
Link: https://leetcode.com/problems/palindrome-permutation/
## 思路
### 思路一
计算每个字母出现的频率，如果有两个奇数，就会false
### 思路二
One pass 用set找有几个数出现了奇数次
## Code
### 思路一

class Solution {
    public boolean canPermutePalindrome(String s) {
        int[] cnt = new int[26];
        char[] charArray = s.toCharArray();
        for(int i = 0;i < charArray.length;i++){
            cnt[charArray[i]-'a']++;
        }
        boolean flag = false;
        for(int i = 0;i < 26;i++){
            if(cnt[i]%2!=0){
                if(flag){
                    return false;
                }
                else{
                    flag = true;
                }
            }
        }
        return true;
    }
}

### 思路二

class Solution {
    public boolean canPermutePalindrome(String s) {
        Set<Character> set = new HashSet<>();
        for(int i = 0;i < s.length();i++){
            if(set.contains(s.charAt(i))){
                set.remove(s.charAt(i));
            }
            else{
                set.add(s.charAt(i));
            }
        }
        return set.size()<=1;
    }
}