原题链接在这里：

题目：

Given a string s, return all the palindromic permutations (without duplicates) of it. Return an empty list if no palindromic permutation could be form.

For example:

Given s = "aabb", return ["abba", "baab"].

Given s = "abc", return [].

题解：

与相似.

先判断是否palindrome, 若不是返回空的res. 若是，先判断是否有一个奇数位，若有，改char放中间. 然后两边分别加.

Time Complexity: O(2^n). Space: O(n)层stack.

AC Java:

1 public class Solution { 2     public List
     
       generatePalindromes(String s) { 3         List
      
        res = new ArrayList
       
        (); 4         int [] map = new int[256]; 5         for(int i = 0; i
        
          res){29         if(cur.length() == len){30             res.add(new String(cur));31             return;32         }33         for(int i = 0; i