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/* ************************************************************************** */
/* */
/* ::: :::::::: */
/* libft_rbt.h :+: :+: :+: */
/* +:+ +:+ +:+ */
/* By: charles <charles.cabergs@gmail.com> +#+ +:+ +#+ */
/* +#+#+#+#+#+ +#+ */
/* Created: 2020/04/26 16:09:51 by charles #+# #+# */
/* Updated: 2020/04/26 20:25:36 by charles ### ########.fr */
/* */
/* ************************************************************************** */
#ifndef LIBFT_RBT_H
# define LIBFT_RBT_H
/*
** \file libft_rbt.h
** \brief Red-black tree
**
** Rules: (from wikipedia)
** 1. Each node is either red or black.
** 2. The root is black. This rule is sometimes omitted. Since the root can
** always be changed from red to black, but not necessarily vice versa,
** this rule has little effect on analysis.
** 3. All leaves (NULL) are black.
** 4. If a node is red, then both its children are black.
** 5. Every path from a given node to any of its descendant NULL nodes goes
** through the same number of black nodes.
**
**
** Unbalance case:
**
** 1. Node and parent are both red
**
** B1
** \ left rot color swap
** > R2 --> R2 --> B2
** \ / \ / \
** > R3 B1 R3 R1 R3
**
** 2. Node and parent are both red and uncle node is red
**
** B2 R2
** / \ color swap / \
** uncle> R1 R3 --> B1 B3
** \ \
** R4 R4
*/
# include <stdlib.h>
/*
** \brief Red-black tree color enum
** \param FTRBT_COLOR_RED color red
** \param FTRBT_COLOR_BLACK color black
*/
enum e_ftrbt_color
{
FTRBT_COLOR_RED = 0,
FTRBT_COLOR_BLACK,
};
/*
** \brief Red-black tree struct
** \param left Left node
** \param right Right node
** \param data Pointer to data
** \param parent Parent node
** \param color Color of the node
** \note The first 3 attricutes are the same
** as t_ftbt (binary tree) struct
** which means that we can use all functions
** of binary tree on red-black tree.
*/
typedef struct s_ftrbt
{
struct s_ftrbt *left;
struct s_ftrbt *right;
void *data;
struct s_ftrbt *parent;
enum e_ftrbt_color color;
} t_ftrbt;
t_ftrbt *ft_rbtnew(void *data, enum e_ftrbt_color color);
void ft_rbtrotate_right(t_ftrbt **tree);
void ft_rbtrotate_left(t_ftrbt **tree);
t_ftrbt *ft_rbtinsert(
t_ftrbt *tree,
void *data,
int (*cmp)(void*, void*));
#endif
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