Sort Anagrams

cc150 Question 11.2 Sort array of string that anagrams next to each other. 

(leetcode 也有类似题目）

Solution 1： 借助Arrays.sort, 需要重写comparator。

    public static class AnagramComparator implements Comparator<String> {
        
        //***********need learn more about comparator***********************//
        /*
         * The ordering imposed by a comparator c on a set of elements S is said to be consistent with equals 
         * if and only if c.compare(e1, e2)==0 has the same boolean value as e1.equals(e2) for every e1 and e2 in S.(non-Javadoc)
         * @see java.util.Comparator#compare(java.lang.Object, java.lang.Object)
         */
        public int compare(String s1, String s2) {
            return sortChars(s1).compareTo(sortChars(s2));//compareTo(String anotherString)
            /*
             *  The result <0  if this String object lexicographically precedes the argument string. 
             *  The result>0  if this String object lexicographically follows the argument string. 
             *  The result == 0 if the strings are equal; 
             */
        }
        public String sortChars(String s) {
            //lee  -> eel;  
            char[] content = s.toCharArray();
            Arrays.sort(content);//sort alph in order
            return new String(content);
        }
    }

Solution 2： Hashtable

 hashtable 存储<key, List<String>anagrams>, 这里key可以简单的将string sort。

public static void sortAnagrams(String[] array){
        Hashtable<String,LinkedList<String>> htable = new Hashtable<String, LinkedList<String>>();
        
        //store key in hashtable
        for(String s: array){
            String key = sortString(s);
            if(!htable.containsKey(key)) {
                htable.put(key, new LinkedList<String>());
            }
            //not else cause must add s to linkedlist
            LinkedList<String> anagrams = htable.get(key);
            anagrams.push(s);
        }
        // Convert hash table to array 
        int index = 0;
        
        for (String key : htable.keySet()) {
            LinkedList<String> list = htable.get(key);
            
            for (String t : list) {
                array[index] = t;
                index++;
            }
        }
        
        
    }