void delete_case5(rb_node* n, rb_tree* tree) {
rb_node* s = sibling(n);
/* this if statement is trivial,
due to Case 2 (even though Case two changed the sibling to a sibling's child,
the sibling's child can't be red, since no red parent can have a red child). */
/* the following statements just force the red to be on the left of the left of the parent,
or right of the right, so case six will rotate correctly. */
if (s->color == BLACK) {
if ((n == n->parent->left) &&
(s->right->color == BLACK) &&
(s->left->color == RED)) { /* this last test is trivial too due to cases 2-4. */
s->color = RED;
s->left->color = BLACK;
rotate_right(s, tree);
} else if ((n == n->parent->right) &&
(s->left->color == BLACK) &&
(s->right->color == RED)) {/* this last test is trivial too due to cases 2-4. */
s->color = RED;
s->right->color = BLACK;
rotate_left(s, tree);
}
}
delete_case6(n, tree);
}
/**
* Do following while the current node u is double black or it is not root. Let sibling of node be s.
* @brief \n(a): If sibling s is black and at least one of sibling’s children is red, perform rotation(s). Let the red child of s be r. This case can be divided in four subcases depending upon positions of s and r.
* \n(i) Left Left Case (s is left child of its parent and r is left child of s or both children of s are red). This is mirror of right right case shown in below diagram.
* \n(ii) Left Right Case (s is left child of its parent and r is right child). This is mirror of right left case shown in below diagram.
* \n(iii) Right Right Case (s is right child of its parent and r is right child of s or both children of s are red)
* \n(iv) Right Left Case (s is right child of its parent and r is left child of s)
* @param t is the tree root.
* @param n is the node at which deletion is taking place.
*/
void delete_case5(rbtree t, node n)
{
if (n == n->parent->left && node_color(sibling(n)) == BLACK && node_color(sibling(n)->left) == RED && node_color(sibling(n)->right) == BLACK)
{
sibling(n)->color = RED;
sibling(n)->left->color = BLACK;
rotate_right(t, sibling(n));
}
else if (n == n->parent->right && node_color(sibling(n)) == BLACK && node_color(sibling(n)->right) == RED && node_color(sibling(n)->left) == BLACK)
{
sibling(n)->color = RED;
sibling(n)->right->color = BLACK;
rotate_left(t, sibling(n));
}
delete_case6(t, n);
}
static void delete_case5(L_RBTREE *t, node *n) {
if (n == n->parent->left &&
node_color(sibling(n)) == L_BLACK_NODE &&
node_color(sibling(n)->left) == L_RED_NODE &&
node_color(sibling(n)->right) == L_BLACK_NODE) {
sibling(n)->color = L_RED_NODE;
sibling(n)->left->color = L_BLACK_NODE;
rotate_right(t, sibling(n));
} else if (n == n->parent->right &&
node_color(sibling(n)) == L_BLACK_NODE &&
node_color(sibling(n)->right) == L_RED_NODE &&
node_color(sibling(n)->left) == L_BLACK_NODE) {
sibling(n)->color = L_RED_NODE;
sibling(n)->right->color = L_BLACK_NODE;
rotate_left(t, sibling(n));
}
delete_case6(t, n);
}
void delete_case5(struct rbtree *t, rbtree_node *n)
{
if (n == n->parent->left &&
get_color(sibling(n)) ==RB_BLACK &&
get_color(sibling(n)->left) == RB_RED &&
get_color(sibling(n)->right) == RB_BLACK)
{
sibling(n)->color = RB_RED;
sibling(n)->left->color =RB_BLACK;
rotate_right(sibling(n),t);
}
else if (n == n->parent->right &&
get_color(sibling(n)) == RB_BLACK &&
get_color(sibling(n)->right) == RB_RED &&
get_color(sibling(n)->left) == RB_BLACK)
{
sibling(n)->color = RB_RED;
sibling(n)->right->color = RB_BLACK;
rotate_left(sibling(n),t);
}
delete_case6(t, n);
}
static inline void
delete_case5(struct RBTREE_TYPENAME* target, struct RBTREE_NODE* P,
struct RBTREE_NODE* N, struct RBTREE_NODE* S)
{
valgrind_assert(S->color == BLACK);
if ((N == P->left) &&
(S->right == NULL || S->right->color == BLACK))
{
valgrind_assert(S->left->color == RED);
S->color = RED;
S->left->color = BLACK;
rotate_right(target, S);
}
else if ((N == P->right) &&
(S->left == NULL || S->left->color == BLACK))
{
valgrind_assert(S->right->color == RED);
S->color = RED;
S->right->color = BLACK;
rotate_left(target, S);
}
delete_case6(target, N);
}
void Tree::delete_case5()
{
//if sibling is black
if(!(sibling()->red))
{
//if siblings family has a single red, we have to make sure that the opposite
//child of the sibling is red which case 6 solvse
if(this == parent->left && !sibling()->right->red && sibling()->left->red)
{
sibling()->red = true;
sibling()->left->red = false;
rotate_right(sibling());
}
else if(this == parent->right &&
!sibling()->left->red && sibling()->right->red)
{
sibling()->red = true;
sibling()->right->red = false;
rotate_left(sibling());
}
}
delete_case6();
}
