Earth/Taylor

lib/exercises.rb

@@ -1,19 +1,28 @@
 
 # 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*k)
+# Space Complexity: O(n)
 
 def grouped_anagrams(strings)
-  raise NotImplementedError, "Method hasn't been implemented yet!"
+  hash = Hash.new { |k, v| k[v] = [] }
+  strings.each do |word|
+    hash[word.chars.sort.join] << word
+  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*k)
+# Space Complexity: O(n)
 def top_k_frequent_elements(list, k)
-  raise NotImplementedError, "Method hasn't been implemented yet!"
+  hash = {}
+  list.each do |num|
+    hash[num] ? hash[num] += 1 : hash[num] = 1
+  end
+  sorted = hash.sort_by{ |k, v| -v }
+  sorted[0...k].map { |num, count| num }
 end
 
 
@@ -25,5 +34,50 @@ def top_k_frequent_elements(list, k)
 # Time Complexity: ?
 # Space Complexity: ?
 def valid_sudoku(table)
-  raise NotImplementedError, "Method hasn't been implemented yet!"
+  store = {
+    rows: {},
+    cols: {},
+    square: {}
+  }
+  i = 0
+  j = 0
+  while i < 9
+    while j < 9
+      box = table[i][j]
+      if !store[:rows][i] && box != "."
+        store[:rows][i] = []
+        store[:rows][i].push(box)
+      elsif box != "." && !store[:rows][i].include?(box)
+        store[:rows][i].push(box)
+      elsif store[:rows][i] && store[:rows][i].include?(box)
+        return false
+      end
+      if !store[:cols][j] && box != "."
+        store[:cols][j] = []
+        store[:cols][j].push(box)
+      elsif box != "." && !store[:cols][j].include?(box)
+        store[:cols][j].push(box);
+      elsif store[:cols][j] && store[:cols][j].include?(box)
+        return false
+      end
+
+      square_row = ((i+1).to_f / 3.0).ceil
+      square_col = ((j+1).to_f / 3.0).ceil
+      square_id = "#{square_row}-#{square_col}"
+      # square_id = j+1
+      puts store[:square]
+
+      if !store[:square][square_id] && box != "."
+        store[:square][square_id] = []
+        store[:square][square_id].push(box)
+      elsif box != "." && !store[:square][square_id].include?(box)
+        store[:square][square_id].push(box)
+      elsif store[:square][square_id] && store[:square][square_id].include?(box)
+        return false
+      end
+      j += 1
+    end
+    i += 1
+  end
+  return true
 end

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 = [