Earth | Ana

lib/exercises.rb

@@ -1,26 +1,55 @@
 
 # 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!"
+  hash = {}
+  return [] if strings.nil? || strings.empty?
+
+  strings.each do |string|
+    key = string.chars.sort.join
+    if hash.include?(key)
+      hash[key] << string
+    else
+      hash[key] = [string]
+    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)
+# 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.each do |element|
+    if hash[element]
+      hash[element] += 1
+    else
+      hash[element] = 1
+    end
+  end
+
+  sorted = hash.sort_by {|key, value| -value }
+  result = []
+  k.times do |index|
+    result << sorted[index].first
+  end
+    return 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 
+#   The same digit cannot appear twice or moregit in the same 
 #   row, column or 3x3 subgrid
 # Time Complexity: ?
 # Space Complexity: ?