diff --git a/lib/exercises.rb b/lib/exercises.rb
index e1b3850..6f8e3a0 100644
--- a/lib/exercises.rb
+++ b/lib/exercises.rb
@@ -1,19 +1,58 @@
 
 # This method will return an array of arrays.
 # Each subarray will have strings which are anagrams of each other
-# Time Complexity: ?
-# Space Complexity: ?
+# Time Complexity: 0(1)
+# Space Complexity: 0(n)
 
 def grouped_anagrams(strings)
-  raise NotImplementedError, "Method hasn't been implemented yet!"
+  return [] if strings.empty?
+  return [strings] if strings.size == 1
+
+  hash1 = {}
+
+  # this is the original str
+  strings.each do |str|
+  
+    # this is the sorted str
+    word = str.split("").sort.join("")
+  
+    # check hash for word 
+    # if not exist, set str as hash value
+    if hash1[word].nil? 
+      hash1[word] = [str]
+    else
+      # or shovel str as hash value
+      hash1[word] << str
+    end
+  
+  end
+  return hash1.values
 end
 
+
 # This method will return the k most common elements
 # in the case of a tie it will select the first occuring element.
-# Time Complexity: ?
-# Space Complexity: ?
+# Time Complexity: 0(1)
+# Space Complexity: 0(n)
+
 def top_k_frequent_elements(list, k)
-  raise NotImplementedError, "Method hasn't been implemented yet!"
+    return [] if list.empty?
+
+    hash1 = {}
+
+  list.each do |element|
+    if hash1[element]
+      hash1[element] += 1
+    else
+      hash1[element] = 1
+    end
+  end
+  sorted = hash1.sort_by {|key, value| -value }
+  result = []
+  k.times do |index|
+    result << sorted[index][0]
+  end
+    return result
 end