diff --git a/.vscode/launch.json b/.vscode/launch.json
new file mode 100644
index 0000000..ec2c85c
--- /dev/null
+++ b/.vscode/launch.json
@@ -0,0 +1,12 @@
+{
+    "version": "0.2.0",
+    "configurations": [
+
+        {
+            "name": "Debug Local File",
+            "type": "Ruby",
+            "request": "launch",
+            "cwd": "${workspaceRoot}",
+            "program": "${file}" }
+    ]
+}
\ No newline at end of file
diff --git a/lib/exercises.rb b/lib/exercises.rb
index e1b3850..416639f 100644
--- a/lib/exercises.rb
+++ b/lib/exercises.rb
@@ -1,29 +1,123 @@
 
 # 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(nm) where n is array length(words) and m is word length(letters)
+# Space Complexity: O(n)
 
 def grouped_anagrams(strings)
-  raise NotImplementedError, "Method hasn't been implemented yet!"
+  return [] if strings.nil?
+  return [] if strings.empty?
+
+  hash = {}
+
+  strings.each do |word|
+    letters = word.split("").sort
+
+    if hash[letters] # if it has the sorted letters
+      hash[letters] << word
+    else
+      hash[letters] = [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 log n) for using sort
+# Space Complexity: O (n)
 def top_k_frequent_elements(list, k)
-  raise NotImplementedError, "Method hasn't been implemented yet!"
-end
 
+  return [] if list.nil? || list.empty?
+
+  if k.nil?
+    raise ArgumentError,"k was not provided"
+  end
+
+  frequent = Hash.new(0)
+
+  list.each do |num|
+    frequent[num] += 1
+  end
+
+  results = frequent.sort_by{|num , frequency| -frequency }
+  results[0...k].map{|num , frequency| num }
+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: ?
+#   row, column or the 9 3x3 subgrid
+# Time Complexity: O(1) for a 9 block sudoku
+# Space Complexity: O(n) for the hash table
 def valid_sudoku(table)
-  raise NotImplementedError, "Method hasn't been implemented yet!"
+  if table.nil? || table.empty?
+    raise ArgumentError,'no table provided'
+  end
+
+  # row check
+  table.each do |row|
+    row_hash = {}
+    row.each do |input|
+      if validate_sudoku_input(input)
+        if row_hash[input]
+          false
+        else
+          row_hash[input] = true
+        end
+      end
+    end
+  end
+
+  # column check
+  i = 0
+  while i < 9
+    col_hash = {}
+    table.each do |row|
+      input = row[i]
+      if validate_sudoku_input(input)
+        if col_hash[input]
+          false
+        else
+          col_hash[input] = true
+        end
+      end
+    end
+    i += 1
+  end
+
+  # 9 3x3 block
+  [0,3,6].each do |rows| # created array for rows
+    [0,3,6].each do |columns| # created array for columns
+      return false unless sudoku_3x3_block(rows, columns, table)
+    end
+  end
+
+  true
 end
+
+
+def validate_sudoku_input(value)
+  if value != "." && value =~ /[^123456789]/
+    false
+  end
+end
+
+def sudoku_3x3_block(rows, columns, table)
+  block_hash = {}
+  (rows...rows+3).each do |row|
+    (columns...columns+3).each do |column|
+      input = table[row][column]
+      return false unless validate_sudoku_input(input)
+      if block_hash[input]
+        false
+      else
+        block_hash[input] = true
+      end
+    end
+  end
+  true
+end
\ No newline at end of file
diff --git a/test/exercises_test.rb b/test/exercises_test.rb
index 74646dc..8d09b1c 100644
--- a/test/exercises_test.rb
+++ b/test/exercises_test.rb
@@ -151,7 +151,7 @@
     end
   end
 
-  xdescribe "valid sudoku" do
+  describe "valid sudoku" do
     it "works for the table given in the README" do
       # Arrange
       table = [
@@ -236,4 +236,4 @@
       expect(valid).must_equal false
     end
   end
-end
+end
\ No newline at end of file