V.1 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.
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V.1 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.
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Program name: push_swap Turn in files: Makefile, *.h, *.c Makefile: NAME, all, clean, fclean, re Arguments: stack a: A list of integers External functs. • read, write, malloc, free, exit • ft_printf and any equivalent YOU coded Libft authorized: Yes Description: Sort stacks
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My approach:
- Before everything, I calculate the actual indexes of each element in the order. So I sort the elements and according to their order of magnitude I give them indexes. (the smallest number is 0 and the biggest is input amount)
- I push all the elements (except the last three) from stack A to stack B.
- Then I sort stack A (the 3 elements).
- Then I calculate the desired position of stack B items in stack A according to their index (step 1)
- Then I calculate the cost of moving each element to the desired location.
- Then I find the element with minimum cost.
- Then I execute some rotations / reverse rotations to put the minimum costelement in the right place in stack B.
- Then I update from step 4 and do this until nothing is left in B.
- Then I do the final rotation in A so they become in the right order.
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My grade: grade 5 for 100 numbers grade 4 for 500 numbers
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a good guide:
https://www.codequoi.com/en/push_swap-efficient-positional-sorting-algorithm/