Bulls and Cows

Bulls and Cows (also known as Pigs and Bulls or Bulls and Cleots or 1A 2B Guess Number) is an old code-breaking paper and pencil game for two players, similar to the popular board game Mastermind.

It is a game with numbers that may date back a century or more. It can be played against the machine with three different levels: Easy, Normal or Hard!

Instructions:

The goal of the game is to discover the 4 secret digits generated randomly. You play against iRobot, an artificial intelligence that will challenge you and will try to discover their own secret number before than you. To play, enter 4 digits and press OK. The game will give you an answer: 1B means that 1 one of your 4 numbers is correct; 1C means that 1 of your numbers is correct but is in wrong order.

Example:
Secret is number: 4271
You enter: 1234
Answer: 1B and 2C. (The bull(B) is '2', the cows(C) are '4' and '1')

The first one to reveal the other's secret number wins the game!

Do you dare beat iRobot and exercise your brain!?