"because swap_push isn’t as natural."
push_swap is a very simple and a highly straightforward algorithm project where we sort data.
we have at our disposal a set of integer values, 2 stacks, and a set of instructions to manipulate both stacks.
our gois to write a program in c called push_swap which calculates and displays on the standard output the smallest program that sorts the integers received as arguments.
this program is made up of solely push swap language instructions.
here are some resources i used:
• push swap — a journey to find most efficient sorting algorithm
• push_swap: the least amount of moves with two stacks
| key | instruction | action |
|---|---|---|
sa |
swap a | swap the top two elements of stack a. if 1 or no elements - no action |
sb |
swap b | swap the top two elements of stack b. if 1 or no elements - no action |
ss |
swap a & swap b | sa and sb at the same time. |
pa |
push a | move the top element of stack b to the top of a. if b is empty - no action |
pb |
push b | move the top element of stack a to the top of b. if a is empty - no action |
ra |
rotate a | shift all elements of a up by 1, first element becomes the last |
rb |
rotate b | shift all elements of b up by 1, first element becomes the last |
rr |
rotate a & rotate b | ra and rb at the same time. |
rra |
reverse rotate a | shift all elements of a down by 1, last element becomes the first |
rrb |
reverse rotate b | shift all elements of b down by 1, last element becomes the first |
rrr |
reverse rotate a + reverse rotate b | rra and rrb at the same time |
i used a positional sorting algorithm, it sorts by index and position.
this algorithm is very efficient: its results are well below the limits that the push_swap evaluation imposes.
here you can see how it performs, thanks to this visualiser by Niimphu.
• to get full 5 points when working with 100 values, the list of instructions must be less than 700 (mine ranges from 550 to 640):
• to get full 5 points when working with 500 values, the list of instructions must be less than 5500 (mine ranges from 4500 to 5000):
-
clone this repository:
git clone git@github.com:idleira/push_swap.git push_swap && cd push_swap -
compile the project with
make -
give the algorithm a random amount of negative and/or positive numbers, which cannot be duplicated:
./push_swap 2 9 6 10 67→ the output will look like this:
pb pb ra pa rra pa, to visualize these operations use the visualizer (duh).
