Leaves - Bri

lib/exercises.rb

@@ -1,30 +1,42 @@
-
-
 # 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 log n)
+# Space Complexity: O(n)
 
 def grouped_anagrams(strings)
-  raise NotImplementedError, "Method hasn't been implemented yet!"
+  hash = {}
+
+ strings.each do | word | 
+  key = word.chars.sort.join
+  if hash.key?(key)
+    hash[key] << word 
+  else
+    hash[key] = [word]
+  end
+ end 
+  result = []
+  hash.each do | key, value |
+    result << hash[key]
+  end
+  return result 
 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 log n)
+# Space Complexity: O(n)
 def top_k_frequent_elements(list, k)
-  raise NotImplementedError, "Method hasn't been implemented yet!"
+  if list.length == 0
+    return []
+  end
+  hash = Hash.new(0)
+  list.each do |num|
+    hash[num] += 1
+  end
+  result = hash.sort_by{|num, frequency| -frequency} # descending order
+  final_result = []
+  k.times do |i|
+    final_result << result[i][0]
+  end
+  return final_result
 end
-
-
-# This method will return the true if the table is still
-#   a valid sudoku table.
-#   Each element can either be a ".", or a digit 1-9
-#   The same digit cannot appear twice or more in the same 
-#   row, column or 3x3 subgrid
-# Time Complexity: ?
-# Space Complexity: ?
-def valid_sudoku(table)
-  raise NotImplementedError, "Method hasn't been implemented yet!"
-end