Nara

lib/exercises.rb

@@ -2,19 +2,46 @@
 
 # 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: O(n)
+# Space Complexity: O(n)
 
 def grouped_anagrams(strings)
-  raise NotImplementedError, "Method hasn't been implemented yet!"
+  return [] if strings.empty?
+  hash = {}
+  strings.each do |string|
+    sorted_string = string.split("").sort.join
+    if hash[sorted_string]
+      hash[sorted_string] << string
+    else 
+      hash[sorted_string] = [string]
+    end
+  end
+  return hash.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: O(n)
+# Space Complexity: 0(n)
 def top_k_frequent_elements(list, k)
-  raise NotImplementedError, "Method hasn't been implemented yet!"
+  hash = {}
+  frequent_elements =[]
+  return [] if k == 0 || list.empty?
+
+  list.each do |element|
+    if hash[element]
+      hash[element] += 1
+    else 
+      hash[element] = 1
+    end
+  end
+  sorted_arrays = hash.sort
+
+  k.times do |i|
+    frequent_elements << sorted_arrays[i][0]
+  end
+
+  return frequent_elements
 end
 
 

test/exercises_test.rb

@@ -68,7 +68,7 @@
     end
   end
 
-  xdescribe "top_k_frequent_elements" do
+  describe "top_k_frequent_elements" do
     it "works with example 1" do
       # Arrange
       list = [1,1,1,2,2,3]