Given an array of strings strs, group the anagrams together. You can return the answer in any order.
An Anagram is a word or phrase formed by rearranging the letters of a different word or phrase, typically using all the original letters exactly once.
Example 1:
Input: strs = ["eat","tea","tan","ate","nat","bat"]
Output: [["bat"],["nat","tan"],["ate","eat","tea"]]
public List<List<String>> groupAnagrams(String[] strs) {
if (strs == null || strs.length == 0) return new ArrayList<>();
Map<String, List<String>> map = new HashMap<>();
for (String s : strs) {
char[] ca = s.toCharArray();
Arrays.sort(ca);
String keyStr = String.valueOf(ca);
if (!map.containsKey(keyStr)) map.put(keyStr, new ArrayList<>());
map.get(keyStr).add(s);
}
return new ArrayList<>(map.values());
}
