Earth - Ting-Yi

lib/binary_to_decimal.rb

@@ -4,6 +4,31 @@
 # The least significant bit is at index 7.
 # Calculate  and return the decimal value for this binary number using
 # the algorithm you devised in class.
+
+# Binary to Decimal
 def binary_to_decimal(binary_array)
-  raise NotImplementedError
+  array_length = binary_array.length
+  num = 0
+  index = 0
+  while array_length > 0
+    num += binary_array[index].to_i * 2 ** (array_length - 1)
+    array_length -= 1
+    index += 1
+  end 
+  return num
 end
+
+### Decimal to Binary
+# def decimal_to_binary(number_base_ten)
+#   quotient = number_base_ten.divmod(2)[0]
+#   modulus = Array(number_base_ten.divmod(2)[1])
+#   until quotient == 0
+#     modulus.unshift(quotient.divmod(2)[1])
+#     quotient = quotient.divmod(2)[0]
+#   end
+#   return "For #{ number_base_ten }, its binary number is \"#{ modulus.join }\""
+# end
+
+# puts decimal_to_binary(255)
+# puts decimal_to_binary(456)
+# puts decimal_to_binary(9)