Leah - Space

lib/exercises.rb

@@ -1,19 +1,54 @@
 
 # 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) - n is number of words in the array
+# Space Complexity: O(n) - n is number of words in the array
 def grouped_anagrams(strings)
-  raise NotImplementedError, "Method hasn't been implemented yet!"
+  return [] if strings.empty?
+
+  hash = {}
+
+  strings.each do |word|
+    sorted_word = word.chars.sort.join
+    if hash[sorted_word]
+      hash[sorted_word] << word
+    else
+      hash[sorted_word] = []
+      hash[sorted_word] << word
+    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) - n is length of list
+# Space Complexity: O(n) - n is the length of the list
 def top_k_frequent_elements(list, k)
-  raise NotImplementedError, "Method hasn't been implemented yet!"
+  return [] if list.empty?
+  return list if list.size == 1
+  return [list[0]] if k == 1
+
+  hash = {}
+  list.each do |num|
+    if hash[num]
+      hash[num] += 1
+    else
+      hash[num] = 1
+    end
+  end
+
+  sorted_nums = hash.sort_by{|num,count| count}.reverse
+
+  most_freq = []
+  i = 0
+  k.times do
+    most_freq << sorted_nums[i][0]
+    i+=1
+  end
+
+  return most_freq  
 end