extern int
ct_bintree_remove(node_t **rootaddr, PyObject *key)
{
node_t *node, *parent, *replacement;
int direction, cmp_res, down_dir;
node = *rootaddr;
if (node == NULL)
return 0;
parent = NULL;
direction = 0;
while (1) {
cmp_res = ct_compare(key, KEY(node));
if (cmp_res == 0)
{
if ((LEFT_NODE(node) != NULL) && (RIGHT_NODE(node) != NULL)) {
parent = node;
direction = RIGHT;
replacement = RIGHT_NODE(node);
while (LEFT_NODE(replacement) != NULL) {
parent = replacement;
direction = LEFT;
replacement = LEFT_NODE(replacement);
}
LINK(parent, direction) = RIGHT_NODE(replacement);
ct_swap_data(node, replacement);
node = replacement;
}
else {
down_dir = (LEFT_NODE(node) == NULL) ? RIGHT : LEFT;
if (parent == NULL)
{
*rootaddr = LINK(node, down_dir);
}
else {
LINK(parent, direction) = LINK(node, down_dir);
}
}
ct_delete_node(node);
return 1;
}
else {
direction = (cmp_res < 0) ? LEFT : RIGHT;
parent = node;
node = LINK(node, direction);
if (node == NULL)
return 0;
}
}
}
void
ct_bintree_remove(node_t **rootaddr, node_t *node)
{
node_t **pnode = NULL;
node_t *tmp;
if (*rootaddr == node) {
// the node is the root
pnode = rootaddr;
} else {
node_t *parent = PARENT_NODE(node);
if (LEFT_NODE(parent) == node) {
pnode = &LEFT_NODE(parent);
} else {
pnode = &RIGHT_NODE(parent);
}
}
if (LEFT_NODE(node) == NULL) {
// replace the root with the right sub-tree
tmp = *pnode = RIGHT_NODE(node);
if (tmp != NULL) {
PARENT_NODE(tmp) = PARENT_NODE(node);
}
ct_delete_node(node);
} else if (RIGHT_NODE(node) == NULL) {
// replace the node with the left sub-tree
tmp = *pnode = LEFT_NODE(node);
PARENT_NODE(tmp) = PARENT_NODE(node);
ct_delete_node(node);
} else {
// both left and right sub-tree is non-null, replace by smallest key in right sub-tree
node_t **pleftmost = &RIGHT_NODE(node);
node_t *leftmost = RIGHT_NODE(node); // assert leftmost != NULL
while ((tmp = LEFT_NODE(leftmost)) != NULL) {
pleftmost = &LEFT_NODE(leftmost);
leftmost = tmp;
}
// found the leftmost node, copy its data to the root, then remove the left most node
ct_swap_data(node, leftmost);
tmp = *pleftmost = RIGHT_NODE(leftmost);
if (tmp != NULL) {
PARENT_NODE(tmp) = PARENT_NODE(leftmost);
}
ct_delete_node(leftmost);
}
}
extern int
rb_remove(node_t **rootaddr, node_t *_node)
{
PyObject *key = KEY(_node);
node_t *root = *rootaddr;
node_t head = { { NULL } }; /* False tree root */
node_t *q, *p, *g; /* Helpers */
node_t *f = NULL; /* Found item */
node_t *tmp;
int dir = 1;
if (root == NULL)
return 0;
/* Set up our helpers */
q = &head;
g = p = NULL;
RIGHT_NODE(q) = root;
/*
Search and push a red node down
to fix red violations as we go
*/
while (q->link[dir] != NULL) {
int last = dir;
int cmp_res;
/* Move the helpers down */
g = p, p = q;
q = q->link[dir];
cmp_res = ct_compare(KEY(q), key);
dir = cmp_res < 0;
/*
Save the node with matching data and keep
going; we'll do removal tasks at the end
*/
if (cmp_res == 0)
f = q;
/* Push the red node down with rotations and color flips */
if (!is_red(q) && !is_red(q->link[dir])) {
if (is_red(q->link[!dir])) {
tmp = rb_single(q, dir);
PARENT_NODE(tmp) = p;
p = p->link[last] = tmp;
}
else if (!is_red(q->link[!dir])) {
node_t *s = p->link[!last];
if (s != NULL) {
if (!is_red(s->link[!last]) &&
!is_red(s->link[last])) {
/* Color flip */
RED(p) = 0;
RED(s) = 1;
RED(q) = 1;
}
else {
int dir2 = g->link[1] == p;
if (is_red(s->link[last])) {
tmp = g->link[dir2] = rb_double(p, last);
PARENT_NODE(tmp) = g;
}
else if (is_red(s->link[!last])) {
tmp = g->link[dir2] = rb_single(p, last);
PARENT_NODE(tmp) = g;
}
/* Ensure correct coloring */
RED(q) = RED(g->link[dir2]) = 1;
RED(g->link[dir2]->link[0]) = 0;
RED(g->link[dir2]->link[1]) = 0;
}
}
}
}
}
/* Replace and remove the saved node */
if (f != NULL) {
ct_swap_data(f, q);
p->link[p->link[1] == q] = q->link[q->link[0] == NULL];
ct_delete_node(q);
}
/* Update the root (it may be different) */
root = head.link[1];
/* Make the root black for simplified logic */
if (root != NULL) {
RED(root) = 0;
PARENT_NODE(root) = NULL;
}
*rootaddr = root;
return (f != NULL);
}
extern int
avl_remove(node_t **rootaddr, PyObject *key)
{
node_t *root = *rootaddr;
int cmp_res;
if (root != NULL) {
node_t *it, *up[32];
int upd[32], top = 0;
it = root;
for (;;) {
if (it == NULL)
return 0;
cmp_res = ct_compare(KEY(it), key);
if (cmp_res == 0)
break;
upd[top] = (cmp_res < 0);
up[top++] = it;
it = it->link[upd[top - 1]];
}
if (it->link[0] == NULL ||
it->link[1] == NULL) {
int dir = it->link[0] == NULL;
if (top != 0)
up[top - 1]->link[upd[top - 1]] = it->link[dir];
else
root = it->link[dir];
ct_delete_node(it);
}
else {
node_t *heir = it->link[1];
upd[top] = 1;
up[top++] = it;
while ( heir->link[0] != NULL ) {
upd[top] = 0;
up[top++] = heir;
heir = heir->link[0];
}
ct_swap_data(it, heir);
up[top - 1]->link[up[top - 1] == it] = heir->link[1];
ct_delete_node(heir);
}
while (--top >= 0) {
int lh = height(up[top]->link[upd[top]]);
int rh = height(up[top]->link[!upd[top]]);
int max = avl_max(lh, rh);
BALANCE(up[top]) = max + 1;
if (lh - rh == -1)
break;
if (lh - rh <= -2) {
node_t *a = up[top]->link[!upd[top]]->link[upd[top]];
node_t *b = up[top]->link[!upd[top]]->link[!upd[top]];
if (height(a) <= height(b))
up[top] = avl_single(up[top], upd[top]);
else
up[top] = avl_double(up[top], upd[top]);
if (top != 0)
up[top - 1]->link[upd[top - 1]] = up[top];
else
root = up[0];
}
}
}
(*rootaddr) = root;
return 1;
}
extern int
rb_remove(node_t **rootaddr, PyObject *key)
{
node_t *root = *rootaddr;
node_t head = { { NULL } };
node_t *q, *p, *g;
node_t *f = NULL;
int dir = 1;
if (root == NULL)
return 0;
q = &head;
g = p = NULL;
RIGHT_NODE(q) = root;
while (q->link[dir] != NULL) {
int last = dir;
int cmp_res;
g = p, p = q;
q = q->link[dir];
cmp_res = ct_compare(KEY(q), key);
dir = cmp_res < 0;
if (cmp_res == 0)
f = q;
if (!is_red(q) && !is_red(q->link[dir])) {
if (is_red(q->link[!dir]))
p = p->link[last] = rb_single(q, dir);
else if (!is_red(q->link[!dir])) {
node_t *s = p->link[!last];
if (s != NULL) {
if (!is_red(s->link[!last]) &&
!is_red(s->link[last])) {
RED(p) = 0;
RED(s) = 1;
RED(q) = 1;
}
else {
int dir2 = g->link[1] == p;
if (is_red(s->link[last]))
g->link[dir2] = rb_double(p, last);
else if (is_red(s->link[!last]))
g->link[dir2] = rb_single(p, last);
RED(q) = RED(g->link[dir2]) = 1;
RED(g->link[dir2]->link[0]) = 0;
RED(g->link[dir2]->link[1]) = 0;
}
}
}
}
}
if (f != NULL) {
ct_swap_data(f, q);
p->link[p->link[1] == q] = q->link[q->link[0] == NULL];
ct_delete_node(q);
}
root = head.link[1];
if (root != NULL)
RED(root) = 0;
*rootaddr = root;
return (f != NULL);
}