🧰 Requirements:

GCC compiler
GNU Make

🔗 Download & Compile

Clone repository:

git clone https://github.com/shuygena/push_swap push_swap

Go to directory:

cd push_swap

For compile program run:
make (push_swap) or make bonus (checker)

📋 Task

The rules

• You have 2 stacks named a and b
• At the beginning:
◦ The stack a contains a random amount of negative and/or positive numbers
which cannot be duplicated
◦ The stack b is empty
• The goal is to sort in ascending order numbers into stack a. To do so you have the
following operations at your disposal:
sa (swap a): Swap the first 2 elements at the top of stack a
Do nothing if there is only one or no elements
sb (swap b): Swap the first 2 elements at the top of stack b
Do nothing if there is only one or no elements
ss : sa and sb at the same time
pa (push a): Take the first element at the top of b and put it at the top of a
Do nothing if b is empty
pb (push b): Take the first element at the top of a and put it at the top of b
Do nothing if a is empty
ra (rotate a): Shift up all elements of stack a by 1
The first element becomes the last one
rb (rotate b): Shift up all elements of stack b by 1
The first element becomes the last one
rr : ra and rb at the same time
rra (reverse rotate a): Shift down all elements of stack a by 1
The last element becomes the first one
rrb (reverse rotate b): Shift down all elements of stack b by 1
The last element becomes the first one
rrr : rra and rrb at the same time.

The "push_swap" program

• You have to write a program named push_swap that takes as an argument the stack a formatted as a list of integers. The first argument should be at the top of the stack (be careful about the order)
• The program must display the smallest list of instructions possible to sort the stack a, the smallest number being at the top
• Instructions must be separated by a ’\n’ and nothing else
• The goal is to sort the stack with the lowest possible number of operations. During the evaluation process, the number of instructions found by your program will be compared against a limit: the maximum number of operations tolerated. If your program either displays a longer list or if the numbers aren’t sorted properly, your grade will be 0.
• If no parameters are specified, the program must not display anything and give the prompt back
• In case of error, it must display "Error" followed by a ’\n’ on the standard error Errors include for example: some arguments aren’t integers, some arguments are bigger than an integer and/or there are duplicates

The "checker" program

• Write a program named checker that takes as an argument the stack a formatted as a list of integers. The first argument should be at the top of the stack (be careful about the order). If no argument is given, it stops and displays nothing
• It will then wait and read instructions on the standard input, each instruction will be followed by ’\n’. Once all the instructions have been read, the program has to execute them on the stack received as an argument
• If after executing those instructions, the stack a is actually sorted and the stack b is empty, then the program must display "OK" followed by a ’\n’ on the standard output
• In every other case, it must display "KO" followed by a ’\n’ on the standard output.
• In case of error, you must display "Error" followed by a ’\n’ on the standard error. Errors include for example: some arguments are not integers, some arguments
are bigger than an integer, there are duplicates, an instruction doesn’t exist and/or is incorrectly formatted

🎓 Tutorial

Usefull information about radix sorting: https://medium.com/nerd-for-tech/push-swap-tutorial-fa746e6aba1e