Fire - Ida - Hash practice

lib/exercises.rb

@@ -1,19 +1,45 @@
 
 # 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.length == 0
+
+  anagrams = Hash.new([])
+  strings.each do |element|
+    sorted_letters = element.sort
+    if anagrams[sorted_letters]
+      anagrams[sorted_letters] << element
+    else
+      anagrams[sorted_letters] = element
+    end
+  end
+  return anagrams.values
+  # strings.each.with_index { |el, i| anagrams[el.downcase.chars.sort.join] += [i] }
+  # anagrams.map { |key, indexes| indexes.map { |i| strings[i] } }
 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: o(n)
 def top_k_frequent_elements(list, k)
-  raise NotImplementedError, "Method hasn't been implemented yet!"
+  return [] if list.length == 0
+  hash_list = {}
+
+  list.each do |number|
+    if hash_list[number]
+      hash_list[number] += 1
+    else
+      hash_list[number] = 1
+    end
+  end
+
+  sortedhash = Hash[hash_list.sort_by { |key, value| -value }[0...k]]
+
+  return sortedhash.keys
 end