group anagrams solution

Author: Jeongwon Na

group-anagrams/njngwn.java

@@ -0,0 +1,21 @@
+// Time Complexity: O(n), n: strs.length
+// Space Complexity: O(m+n), m: strMap.size, n: anagramList.size
+class Solution {
+    public List<List<String>> groupAnagrams(String[] strs) {
+        HashMap<String, ArrayList<String>> strMap = new HashMap<String, ArrayList<String>>();
+
+        for (String str : strs) {
+            char[] charArr = str.toCharArray();
+            Arrays.sort(charArr);
+            String key = String.valueOf(charArr);
+
+            if (strMap.containsKey(key)) {
+                strMap.get(key).add(str);
+            } else {
+                strMap.put(key, new ArrayList<String>(Arrays.asList(str)));
+            }
+        }
+
+        return new ArrayList<>(strMap.values());
+    }
+}