forked from root/public
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
![]() |
3 years ago | |
---|---|---|
.. | ||
audit | 3 years ago | |
README.md | 3 years ago |
README.md
push-swap
Objectives
Push-Swap is a very simple project that uses a Non-Comparative Sorting Algorithm. You have at your disposal a list of int
values, two stacks (a
and b
) and a set of instructions.
You will have to write 2 programs:
- push-swap, which calculates and displays on the standard output the smallest program using push-swap instruction language that sorts integer arguments received.
- checker, which takes integer arguments and reads instructions on the standard output. Once read, checker executes them and displays
OK
if integers are sorted. Otherwise, it will displayKO
.
As said before, you will have two stacks at your disposal. Your goal is to sort the stack a
, that will contain the int
values received, in ascending order, using both stacks and a set of instructions.
These are the instructions that you can use to sort the stack :
pa
push the top first element of stackb
to stacka
pb
push the top first element of stacka
to stackb
sa
swap first 2 elements of stacka
sb
swap first 2 elements of stackb
ss
executesa
andsb
ra
rotate stacka
(shift up all elements of stacka
by 1, the first element becomes the last one)rb
rotate stackb
rr
executera
andrb
rra
reverse rotatea
(shift down all elements of stacka
by 1, the last element becomes the first one)rrb
reverse rotateb
rrr
executerra
andrrb
Example
Init a and b :
2
1
3
6
8
5
= =
a b
---------------------------------------
Exec sa :
1
2
3
6
8
5
= =
a b
---------------------------------------
Exec pb pb pb :
6 3
8 2
5 1
= =
a b
---------------------------------------
Exec rb :
6 2
8 1
5 3
= =
a b
---------------------------------------
Exec rra and rrb (equivalent to rrr):
5 3
6 2
8 1
= =
a b
---------------------------------------
Exec pa pa pa:
1
2
3
5
6
8
= =
a b
The push-swap program
- You have to write a program named push-swap, which will receive as an argument the stack
a
formatted as a list of integers. The first integer should be at the top of the stack. - The program must display the smallest list of instructions possible to sort the stack
a
, with 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 minimum possible number of operations.
- In case of error, you must display
Error
followed by a\n
on the standard error. Errors are understood as: some arguments are not integers and/or there are duplicates. - If there are no arguments, the program does not display anything (0 instructions).
$ go run . "2 1 3 6 5 8"
pb
pb
ra
sa
rrr
pa
pa
$ go run . "0 one 2 3"
Error
$ go run .
$
The checker program
- You have to write a program named checker, which will get 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, checker stops and displays nothing. - Checker will then read instructions on the standard input, each instruction will be followed by
\n
. Once all the instructions have been read, checker will execute them on the stack received as an argument. - If after executing those instructions, stack
a
is actually sorted andb
is empty, then checker must display "OK" followed by a\n
on the standard output. In every other case, checker 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, there are duplicates, an instruction do not exist and/or is incorrectly formatted. - In case of there are no arguments, the program displays nothing.
$ go run ./checker "3 2 1 0"
sa
rra
pb
KO
$ echo -e "rra\npb\nsa\n" | go run ./checker "3 2 one 0"
Error
$ echo -e "rra\npb\nsa\nrra\npa"
rra
pb
sa
rra
pa
$ echo -e "rra\npb\nsa\nrra\npa" | go run ./checker "3 2 1 0"
OK
$ go run ./checker
$
Instructions
- Your project must be written in Go.
- The code must respect the good practices.
- It is recommended to have test files for unit testing.
- The first executable file must be named checker and the second push-swap.
- You have to be able to handle the errors.
Allowed packages
- Only the standard Go packages are allowed
Usage
$ ARG="4 67 3 87 23"; ./push-swap "$ARG" | wc -l
6
$ ARG="4 67 3 87 23"; ./push-swap "$ARG" | go run ./checker "$ARG"
OK
$
If the program checker displays KO, it means that your push-swap came up with a list of instructions that does not sort the list.
This project will help you learn about :
- the use of basic algorithms
- the use of sorting algorithms
- the use of stacks