Bulls, cows and captcha’s

Hi there,

One, two, THREE new code challenges! Not too shabby for just another January week, is it?

Reverse engineer

Standing next to a machine with numeric inputs x and y, and a single numeric output - that evaluates an expression using x, y, the operators + – * / and brackets - you should recover the expression using the machine with inputs of your choice in several turns.

Bulls and Cows

Nicola found a description of the game "Bulls and Cows", popular amongst humans back in the day. He wants to play it with Stephan, but Nicola definitely does not like to lose! That's where we come in. Write a program to help Nicola solve the code in up to seven turns. Yihaaa!

Mono Captcha

Let's teach Stephan recognizing simple numbers. The Robots use monospaced fonts with a low resolution. Your program should read the number shown in an image encoded as a 0-1 2D array.

Happy hacking!