Space - Nora

lib/exercises.rb

@@ -1,19 +1,52 @@
 
 # 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^2) or O(m * n) where m is the number of words and n is the characters
+# Space Complexity: O(n) where n is the number of words in the array
 
 def grouped_anagrams(strings)
-  raise NotImplementedError, "Method hasn't been implemented yet!"
+  hash = {}
+  return [] if strings.empty?
+
+  strings.each do |word|
+    sorted = word.chars.sort
+    if hash[sorted]
+      hash[sorted] << word
+    else
+      hash[sorted] = [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: ?
+# in the case of a tie it will select the first occurring element.
+# Time Complexity: O (n log n) due to sort_by / quick sort - best case. Worst case is O(n^2) if the data is already ordered
+# Space Complexity: O(n)
 def top_k_frequent_elements(list, k)
-  raise NotImplementedError, "Method hasn't been implemented yet!"
+  return [] if list.empty?
+  hash = {}
+
+  list.each do |num|
+    if hash[num]
+      hash[num] =+ 1
+    else
+      hash[num] = 1
+    end
+  end
+
+  sorted_hash = hash.sort_by {|key, value| -value}
+
+  answer = []
+
+  k.times do |i|
+    answer << sorted_hash[i][0]
+  end
+
+  return answer
+
 end
 
 
@@ -24,6 +57,37 @@ def top_k_frequent_elements(list, k)
 #   row, column or 3x3 subgrid
 # Time Complexity: ?
 # Space Complexity: ?
+
+def complete_sudoku
+  return {
+    1 => 1,
+    2 => 1,
+    3 => 1,
+    4 => 1,
+    5 => 1,
+    6 => 1,
+    7 => 1,
+    8 => 1,
+    9 => 1
+  }
+end
+
+
 def valid_sudoku(table)
-  raise NotImplementedError, "Method hasn't been implemented yet!"
+
+  # rows = {}
+  # cols = {}
+  # mini_square = {}
+
+  # i = 0 # current row
+  # j = 0 # current column
+  # until i > 9
+  #   until j > 9
+  #     box = table[i][j];
+  #     j += 1
+  #   end
+  #   i += 1
+  # end
 end
+
+