This is a tiny program for solving the numbers game from the British TV program Cowntown, in which contestants are presented with 6 numbers and a randomly generated target number, and try to construct the target using the 6 numbers and the operations addition, subtraction, multiplication, and division.
This simply brute-forces all possible expressions to find the solution. Expressions are created recursively and to avoid problems with operation orders, they are made in postfix form.
countdown <number_of_numbers(n)> <n_1> <n_2> ... <n_n> <target>
Example:
countdown 6 50 75 100 25 2 1 940
output:
25 * 50 = 1250
2 + 1250 = 1252
75 * 1252 = 93900
93900 / 100 = 939
939 + 1 = 940