LeetCode: Anagrams 解题报告

 1 public class Solution {
 2     public List<String> anagrams(String[] strs) {
 3         List<String> ret = new ArrayList<String>();
 4         
 5         if (strs == null) {
 6             return ret;
 7         }
 8         
 9         HashMap<String, List<String>> map = new HashMap<String, List<String>>();
10         
11         int len = strs.length;
12         for (int i = 0; i < len; i++) {
13             String s = strs[i];
14             
15             // Sort the string.            
16             char[] chars = s.toCharArray();
17             Arrays.sort(chars);
18             String strSort = new String(chars);   
19             
20             // Create a ArrayList for the sorted string.            
21             if (!map.containsKey(strSort)) {
22                 map.put(strSort, new ArrayList<String>());
23             }
24             
25             // Add a new string to the list of the hashmap.
26             map.get(strSort).add(s);
27         }
28         
29         // go through the map and add all the strings into the result.
30         for (Map.Entry<String, List<String>> entry: map.entrySet()) {
31             List<String> list = entry.getValue();
32             
33             // skip the entries which only have one string.
34             if (list.size() == 1) {
35                 continue;
36             }
37             
38             // add the strings into the list.
39             ret.addAll(list);
40         }
41         
42         return ret;
43     }
44 }