[leetcode#267] Palindrome permutation II

problem:

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

For example:

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

Given s = "abc" , return [] .

Analysis:

This problem was very easy, it shares the same idea with "strobogrammatic number""palindrome permutation" to const RUCT IT!!! (pointer!  "len = = 1", the string must a Pilindrome string! Wrong part: if (Len <= 1) {    return  ret;} Errors:input:"A"output:[]expected:["a"]

Solution:

 Public classSolution { PublicList<string>Generatepalindromes (String s) {if(s = =NULL)            Throw NewIllegalArgumentException ("s is null"); List<String> ret =NewArraylist<string> (); intLen =s.length (); if(len = = 0) {            returnret; } HashMap<character, integer> map =NewHashmap<character, integer> ();  for(CharC:s.tochararray ()) {            if(Map.containskey (c)) Map.put (c, Map.get (c)+1); ElseMap.put (c,1); }        intOdd_count = 0; CharOdd_char = ' a ';  for(CharC:map.keyset ()) {            if(Map.get (c)% 2 = = 1) {Odd_count++; Odd_char=C; }        }        if(Odd_count >= 2)            returnret; if(Odd_count = = 1) {SearchPath (map, Odd_char+ "", Len, ret); } Else{searchPath (map,"", Len, ret); }        returnret; }            Private voidSearchPath (Hashmap<character, integer> map, String cur,intTarget, list<string>ret) {String New_cur=cur; intLen =new_cur.length (); if(len = =target)            {Ret.add (new_cur); return; }         for(CharC:map.keyset ()) {            if(Map.get (c) >= 2) {New_cur= c + cur +C; Map.put (c, Map.get (c)+ t);                SearchPath (map, New_cur, Target, ret); Map.put (c, Map.get (c)-T); }        }    }}

[leetcode#267] Palindrome permutation II