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sort_lots.c
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sort_lots.c
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/* ************************************************************************** */
/* */
/* ::: :::::::: */
/* sort_lots.c :+: :+: :+: */
/* +:+ +:+ +:+ */
/* By: fvonsovs <fvonsovs@student.42.fr> +#+ +:+ +#+ */
/* +#+#+#+#+#+ +#+ */
/* Created: 2023/04/16 16:28:35 by fvonsovs #+# #+# */
/* Updated: 2023/04/17 18:03:17 by fvonsovs ### ########.fr */
/* */
/* ************************************************************************** */
#include "push_swap.h"
// gets max bits to represent an index
int get_index_bits(t_stack **stack)
{
t_stack *temp;
int max;
int max_bits;
temp = *stack;
max = temp->index;
max_bits = 0;
while (temp)
{
if (temp->index > max)
max = temp->index;
temp = temp->next;
}
while ((max >> max_bits) != 0)
max_bits++;
return (max_bits);
}
/*
* least significant bit (binary) radix sort
*
* start from least significant bit
* bitwise shift index value i positions
* check if least significant bit is 0 or 1
* distributes between 2 stacks according to least sig bit
*
* Example: Decimal values: 9, 3, 1, 6
* Binary values: 1001, 0011, 0001, 0110
*
* 1. Sort by least significant bit (rightmost bit):
* - Elements with LSB = 0: [0110] (6 in decimal)
* - Elements with LSB = 1: [1001, 0011, 0001] (9, 3, 1 in decimal)
* - Combined stacks: [6, 9, 3, 1]
*
* 2. Sort by the second bit from the right:
* - Elements with LSB = 0: [0110, 0001] (6, 1 in decimal)
* - Elements with LSB = 1: [1001, 0011] (9, 3 in decimal)
* - Combined stacks: [6, 1, 9, 3]
*
* 3. Sort by the third bit from the right:
* - Elements with LSB = 0: [0110, 0011, 0001] (6, 3, 1 in decimal)
* - Elements with LSB = 1: [1001] (9 in decimal)
* - Combined stacks: [6, 3, 1, 9]
*
* 4. Sort by the most significant bit (leftmost bit):
* - Elements with LSB = 0: [0110, 0011, 0001] (6, 3, 1 in decimal)
* - Elements with LSB = 1: [1001] (9 in decimal)
* - Combined stacks: [1, 3, 6, 9]
*
* After processing all bit positions, the numbers are sorted.
*/
int sort_lots(t_stack **stack_a, t_stack **stack_b)
{
t_stack *temp;
int i;
int j;
int size;
int max_bits;
temp = *stack_a;
size = stack_size(*stack_a);
max_bits = get_index_bits(stack_a);
i = -1;
while (++i < max_bits)
{
j = -1;
while (++j < size)
{
temp = *stack_a;
if (((temp->index >> i) & 1) == 0)
pa_pb(stack_a, stack_b, 0);
else
ra_rb(stack_a, stack_b, 1);
}
while (stack_size(*stack_b) != 0)
pa_pb(stack_a, stack_b, 1);
}
return (is_sorted(*stack_a));
}