Tatiana

lib/exercises.rb

@@ -2,19 +2,57 @@
 
 # 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) it must go through the entire list
+# Space Complexity: O(n) we return an array of size n same as the input array
 
 def grouped_anagrams(strings)
-  raise NotImplementedError, "Method hasn't been implemented yet!"
+  string_hash = {}
+
+  return [] if strings.empty?
+
+  # loop through array, 
+  strings.each do |word|
+    sorted_word = word.chars.sort.join
+    if string_hash[sorted_word]
+      string_hash[sorted_word].push(word)
+    else
+      string_hash[sorted_word] = [word]
+    end
+  end
+
+  return string_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(nLogn)
+# Space Complexity: O(n)
 def top_k_frequent_elements(list, k)
-  raise NotImplementedError, "Method hasn't been implemented yet!"
+  element_counts = {}
+  count = 0
+
+  return list if list.empty?
+
+  list.each do |num|
+    if element_counts[num]
+      element_counts[num] += 1
+    else
+      element_counts[num] = 1
+    end
+
+  end
+
+  sorted_hash_array = element_counts.sort_by{ |key, val| -val}
+
+  puts sorted_hash_array.to_s
+  return_array = []
+  k.times do |i|
+  return_array.push(sorted_hash_array[i][0])
+  i += 1
+  end
+
+  return return_array
+
 end
 
 
@@ -27,4 +65,4 @@ def top_k_frequent_elements(list, k)
 # Space Complexity: ?
 def valid_sudoku(table)
   raise NotImplementedError, "Method hasn't been implemented yet!"
-end
+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]