80 lines
2 KiB
C
80 lines
2 KiB
C
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/* ************************************************************************** */
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/* */
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/* ::: :::::::: */
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/* ft_lst_merge_sort.c :+: :+: :+: */
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/* +:+ +:+ +:+ */
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/* By: gtertysh <marvin@42.fr> +#+ +:+ +#+ */
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/* +#+#+#+#+#+ +#+ */
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/* Created: 2017/04/02 06:44:41 by gtertysh #+# #+# */
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/* Updated: 2017/04/02 06:44:43 by gtertysh ### ########.fr */
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/* */
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/* ************************************************************************** */
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#include "libft.h"
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static t_list *merge(t_list *a, t_list *b, int (*cmp)())
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{
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t_list *result;
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result = NULL;
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if (a == NULL)
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return (b);
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else if (b == NULL)
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return (a);
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if (cmp(a->content, b->content))
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{
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result = a;
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result->next = merge(a->next, b, cmp);
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}
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else
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{
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result = b;
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result->next = merge(a, b->next, cmp);
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}
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return (result);
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}
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static void split(t_list *source, t_list **front_ptr, t_list **back_ptr)
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{
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t_list *fast;
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t_list *slow;
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if (source == NULL || source->next == NULL)
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{
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*front_ptr = source;
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*back_ptr = NULL;
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}
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else
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{
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slow = source;
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fast = source->next;
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while (fast != NULL)
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{
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fast = fast->next;
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if (fast != NULL)
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{
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slow = slow->next;
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fast = fast->next;
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}
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}
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*front_ptr = source;
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*back_ptr = slow->next;
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slow->next = NULL;
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}
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}
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void ft_lst_merge_sort(t_list **head_ptr, int (*cmp)())
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{
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t_list *head;
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t_list *a;
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t_list *b;
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head = *head_ptr;
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if ((head == NULL) || (head->next == NULL))
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return ;
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split(head, &a, &b);
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ft_lst_merge_sort(&a, cmp);
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ft_lst_merge_sort(&b, cmp);
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*head_ptr = merge(a, b, cmp);
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}
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