Anagrams.java

/*
 Author:     King, wangjingui@outlook.com
 Date:       Dec 25, 2014
 Problem:    Anagrams
 Difficulty: Easy
 Source:     https://oj.leetcode.com/problems/anagrams/
 Notes:
 Given an array of strings, return all groups of strings that are anagrams.
 Note: All inputs will be in lower-case.

 Solution: Sort the string to see if they're anagrams.
 */

import java.util.Map.Entry; 
public class Solution {
    public List<String> anagrams(String[] strs) {
        ArrayList<String> res = new ArrayList<String>();
        HashMap<String, ArrayList<String>> group = new HashMap<String, ArrayList<String>>();
        if (strs.length == 0) return res;
        for (int i = 0; i < strs.length; ++i) {
            char[] tmp = strs[i].toCharArray();
            Arrays.sort(tmp);
            String s = String.valueOf(tmp);
            if(group.containsKey(s)) 
                (group.get(s)).add(strs[i]);    
            else {
                ArrayList<String> t = new ArrayList<String>();
                t.add(strs[i]);
                group.put(s,t); 
            }
        }
        Iterator<Entry<String, ArrayList<String>>> iter = group.entrySet().iterator();
        while (iter.hasNext()) {
            Map.Entry entry = (Map.Entry) iter.next();
            ArrayList<String> val = (ArrayList<String>) entry.getValue();
            if (val.size() > 1) res.addAll(val);
        }
        return res;
    }
}