Push Swap

About • Subject requirements • Usage

About The Project

This project is about sorting data on a stack, with a limited set of instructions, using the lowest possible number of actions.

I have at my disposal a set of integer values, 2 stacks, and a set of instructions to manipulate both stacks.

Goal? Write a program in C called push_swap which calculates and displays on the standard output list of instructions, that sorts the integers received as arguments.

Subject requirements

• I 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 using following rules:
  • 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.

Usage

To start program:

make
./push_swap 2 1 3 6 5 8