Given a string, we can "shift" each of its letter to its successive letter, for example: "abc" -> "bcd". We can keep "shifting" which forms the sequence:"abc" -> "bcd" -> ... -> "xyz"Given a list of strings which contains only lowercase alphabets, group all strings that belong to the same shifting sequence.For example, given: ["abc", "bcd", "acef", "xyz", "az", "ba", "a", "z"], A solution is:[  ["abc","bcd","xyz"],  ["az","ba"],  ["acef"],  ["a","z"]]

与类似. 维护一个HashMap, key是每个string 的 base型.

Time Complexity: O(n * strings.length), n 是每个string的平均长度.

Space: O(hm.size()), HashMap size.

// "static void main" must be defined in a public class.public class Main {    public static void main(String[] args) {        String[] strs = {"abc", "bcd", "acef", "xyz", "az", "ba", "a", "z"};        List
     
      
       > list = groupStrings(strs);        for(int i=0; i
       
         subList = list.get(i);            for(int j=0; j
        
         > groupStrings(String[] strings) {        if(strings == null || strings.length == 0){            return new ArrayList
         
          
           >(); } Map
           
            > map = new HashMap<>(); for(int i=0; i
            
             ()); } map.get(str).add(strings[i]); } return new ArrayList
             
              
               >(map.values()); } public static String getBase(String str){ if(str == null || str.length()==0){ return str; } StringBuilder sb = new StringBuilder(); int offset = str.charAt(0) - 'a'; for(int i=0; i