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Given an array of strings, group anagrams together.

Example:

Input: ["eat", "tea", "tan", "ate", "nat", "bat"],
Output:
[
  ["ate","eat","tea"],
  ["nat","tan"],
  ["bat"]
]

Note:

• All inputs will be in lowercase.
• The order of your output does not matter.

Solution 1:

class Solution {
    public List<List<String>> groupAnagrams(String[] strs) {
        
        Map<String, List<String>> anMap = new HashMap<String, List<String>>();
        
        List<List<String>> retList = new ArrayList<List<String>>();
        
        for(int i = 0; i<strs.length;i++){
            char[] charArray = strs[i].toCharArray();
            Arrays.sort(charArray);
            String str = new String(charArray);
            if(anMap.containsKey(str)){
                List<String> innerList = anMap.get(str);
                innerList.add(strs[i]);
                anMap.put(str, innerList);
            }else{
                List<String> innerList = new ArrayList<String>();
                innerList.add(strs[i]);
                anMap.put(str, innerList);
            }
        }
        
        for(String key:anMap.keySet()){
            retList.add(anMap.get(key));
        }
        
        return retList;
        
    }
}