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Started implementing btree deletion

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This commit is contained in:
max 🍓
2023-01-18 19:45:58 +00:00
parent 1c0a4bc708
commit a275ca0955
1 changed files with 104 additions and 3 deletions
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107
sandbox/btree/btree.c
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@@ -1,6 +1,7 @@
#include <socks/btree.h>
#include <stddef.h>
#include <stdlib.h>
#include <stdio.h>
#define MAX(a, b) ((a) > (b) ? (a) : (b))
#define MIN(a, b) ((a) < (b) ? (a) : (b))
@@ -8,6 +9,13 @@
#define IS_LEFT_CHILD(p, c) ((p) && (c) && ((p)->b_left == (c)))
#define IS_RIGHT_CHILD(p, c) ((p) && (c) && ((p)->b_right == (c)))
#define HAS_LEFT_CHILD(x) ((x) && ((x)->b_left))
#define HAS_RIGHT_CHILD(x) ((x) && ((x)->b_right))
#define HAS_NO_CHILDREN(x) ((x) && (!(x)->b_left) && (!(x)->b_right))
#define HAS_ONE_CHILD(x) ((HAS_LEFT_CHILD(x) && !HAS_RIGHT_CHILD(x)) || (!HAS_LEFT_CHILD(x) && HAS_RIGHT_CHILD(x)))
#define HAS_TWO_CHILDREN(x) (HAS_LEFT_CHILD(x) && HAS_RIGHT_CHILD(x))
static void rotate_left(btree_t *tree, btree_node_t *x)
{
btree_node_t *y = x->b_right;
@@ -95,7 +103,7 @@ static void rotate_double_right(btree_t *tree, btree_node_t *z)
static void insert_fixup(btree_t *tree, btree_node_t *w)
{
btree_node_t *z = NULL, *y = NULL, *x = NULL;
z = w;
while (z) {
if (z->b_bfactor >= -1 && z->b_bfactor <= 1) {
@@ -136,7 +144,7 @@ void btree_insert(btree_t *tree, btree_node_t *node)
btree_node_t *cur = tree->b_root;
while (1) {
btree_node_t **nextp = NULL;
int bfactor_diff = 0;
if (node->b_key >= cur->b_key) {
nextp = &cur->b_right;
@@ -161,7 +169,100 @@ void btree_insert(btree_t *tree, btree_node_t *node)
insert_fixup(tree, node);
}
static void remove_node_with_no_children(btree_t *tree, btree_node_t *node)
{
printf("remove_node_with_no_children()\n");
btree_node_t *p = node->b_parent;
node->b_parent = NULL;
if (!p) {
tree->b_root = NULL;
} else if (IS_LEFT_CHILD(p, node)) {
p->b_left = NULL;
} else {
p->b_right = NULL;
}
}
static void replace_node_with_one_subtree(btree_t *tree, btree_node_t *node)
{
printf("remove_node_with_one_subtree()\n");
btree_node_t *p = node->b_parent;
btree_node_t *z = NULL;
if (HAS_LEFT_CHILD(node)) {
z = node->b_left;
} else {
z = node->b_right;
}
if (IS_LEFT_CHILD(p, node)) {
p->b_left = z;
} else if (IS_RIGHT_CHILD(p, node)) {
p->b_right = z;
}
z->b_parent = p;
node->b_parent = NULL;
node->b_left = node->b_parent = NULL;
}
static void replace_node_with_two_subtrees(btree_t *tree, btree_node_t *node)
{
printf("remove_node_with_two_subtrees()\n");
btree_node_t *cur = node->b_left;
while (cur->b_right) {
cur = cur->b_right;
}
btree_node_t *p = cur->b_parent;
if (IS_LEFT_CHILD(p, cur)) {
p->b_left = NULL;
p->b_bfactor++;
} else {
p->b_right = NULL;
p->b_bfactor--;
}
p = node->b_parent;
if (p) {
if (IS_LEFT_CHILD(p, node)) {
p->b_left = cur;
} else {
p->b_right = cur;
}
}
cur->b_left = node->b_left;
cur->b_right = node->b_right;
cur->b_bfactor = node->b_bfactor;
cur->b_parent = p;
if (!p) {
tree->b_root = cur;
}
}
void btree_delete(btree_t *tree, btree_node_t *node)
{
btree_node_t *x = NULL;
if (HAS_NO_CHILDREN(node)) {
remove_node_with_no_children(tree, node);
return;
}
if (HAS_ONE_CHILD(node)) {
replace_node_with_one_subtree(tree, node);
return;
}
if (HAS_TWO_CHILDREN(node)) {
replace_node_with_two_subtrees(tree, node);
return;
}
}