Push_swap

WeThinkCode_ Module
Alogrithms - Project 1
Because Swap_push isn’t as natural

Description

This project will make you sort data on a stack, with a limited set of instructions, using the lowest possible number of actions. To succeed you’ll have to manipulate various types of algorithms and choose the one (of many) most appropriate solution for an optimized data sorting.

Objective

The Push_swap project is a very simple and highly effective algorithm project: data will need to be sorted. You have at your disposal a set of int values, 2 stacks and a set of instructions to manipulate both stacks.

The goal? Write 2 programs in C:

• The first, named 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 display KO.
• The second one called push_swap which calculates and displays on the standard output the smallest program using Push_swap instruction language that sorts integer arguments received.

Allowed functions:

• write
• read
• malloc
• free
• exit

Installation

Clone the push_swap repo and change to the repo directory:

git clone https://github.com/veronar/push_swap
cd ./push_swap/push_swap/

Compilation

Push_swap & checker are compiled with a Makefile; to compile, run the follwing command:

make

This will create 2 executables: checker & push_swap.

If any edits are made to the source code the executables can be recompiled using the follwing command:

make re

Usage

Both programs run with with the same rules for input:

• only digits
• numbers only within INT MIN & INT MAX
• no duplicates
• input is read from stdout
• ctrl + d signifies EOF (end of file / input)
• Errors are displayed on stderr

Operations allowed:

• 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 flast element becomes the first one.
• rrb : reverse rotate b - shift down all elements of stack b by 1. The flast element becomes the first one.
• rrr : rra and rrb at the same time.

The programs can be run independantly of each other.
They can also be run simultaneously with the following format:

ARG="4 67 3 87 23"; ./push_swap $ARG | ./checker $ARG

Number of operations done by push_swap can be checked in the follwing way:

ARG="4 67 3 87 23"; ./push_swap $ARG | wc -l

Usage Flags

The following flags can be used with Push_swap (and Checker where relevant):

• -v : Visual mode. Prints stacks to the terminal.
• -c : Colour mode. Prints stacks in colour to the terminal.
• -s : Slow mode. Adds a pause in order to make output more easily readable.
• -o : Shows last operation performed.
• -m : Shows total amount of move / operations done.

Shout-out

Thanks to @FWMoor & @CharlieDeltaZA for major help in optimising my sorting algorithm for large stacks!