[LeetCode 049] Group Anagrams

Group Anagrams

• set a HashMap.
  • The key is string with letters in lexicographic order.
  • The value is index of list containing anagrams in an ArrayList.

Implementation

public class Solution {
    public List<List<String>> groupAnagrams(String[] strs) {
        Arrays.sort(strs);
        List<List<String>> result = new ArrayList<List<String>>();
        HashMap<String, Integer> map = new HashMap<String, Integer>();
        for (int i = 0; i < strs.length; i++) {
            char[] e = strs[i].toCharArray();
            Arrays.sort(e);
            String element = String.valueOf(e);
            if (map.containsKey(element)) {
                result.get(map.get(element)).add(strs[i]);
            }
            else {
                ArrayList<String> list = new ArrayList<String>();
                list.add(strs[i]);
                result.add(list);
                map.put(element, result.size() - 1);
            }
        }
        return result;
    }
}