void BST::drop(int key) {
if(empty())
return;
Node *keyNode = findParent(key);
if(keyNode->key() == key) {
Node *successor = findSuccessor(keyNode);
if(successor == NULL) { // No right subtree.
if(root != keyNode) {
if(keyNode->parent->left == keyNode)
keyNode->parent->left = keyNode->left;
else
keyNode->parent->right = keyNode->left;
}
else root = keyNode->left;
}
else replaceWithSuccessor(keyNode, successor);
keyNode->parent = NULL;
keyNode->left = NULL;
keyNode->right = NULL;
delete keyNode;
}
}
int deleteItem(struct treeNode * node, int item)
{
struct treeNode *parent=0,*del=0;
int type;
if (node==0) return 0;
if (root->item==item && root==node){
parent=0;
del=root;
}
if (node->left!=0 && node->left->item==item ){
parent=node;
del=node->left;
type=0;
}
if (node->right!=0 && node->right->item==item){
parent=node;
del=node->right;
type=1;
}
if (parent==0 && del==0){
int t=deleteItem(node->left,item);
if(t==FALSE_VALUE)t=deleteItem(node->right,item);
return t;
}
else {
if (del->left==0 && del->right==0){
free(del);
if(parent==0) initializeTree();
else if(type==0) parent->left=0;
else parent->right=0;
}
else if (del->left==0){
if (parent==0) root=del->right;
else if (type==0) parent->left=del->right;
else parent->right=del->right;
free(del);
}
else if (del->right==0){
if (parent==0) root=del->left;
else if (type==0) parent->left=del->left;
else parent->right=del->left;
free(del);
}
else{
struct treeNode *scc;
scc=findSuccessor(del,del->item);
int x;
x=del->item;
del->item=scc->item;
scc->item=x;
deleteItem(root,scc->item);
}
return TRUE_VALUE;
}
}
/* Performs a find successor request to a random id */
void Node::randomLookup()
{
int res = id_;
int random_index = RngStream_RandInt(stream, 0, nb_bits - 1);
int random_id = fingers_[random_index];
XBT_DEBUG("Making a lookup request for id %d", random_id);
if (random_id != id_)
res = findSuccessor(random_id);
XBT_DEBUG("The successor of node %d is %d", random_id, res);
}
/** refreshes the finger table of the current node (called periodically) */
void Node::fixFingers()
{
XBT_DEBUG("Fixing fingers");
int id = findSuccessor(id_ + (1U << next_finger_to_fix));
if (id != -1) {
if (id != fingers_[next_finger_to_fix]) {
setFinger(next_finger_to_fix, id);
printFingerTable();
}
next_finger_to_fix = (next_finger_to_fix + 1) % nb_bits;
}
}
// 트리 노드 삭제
void deleteNode(Tree *RBT, Node *node)
{
Node *successor, *fixupNode;
Node *left = node->left;
Node *right = node->right;
Node *p = node->parent;
int nColor = node->color;
// child 0, 1 : 왼쪽노드 없는 경우
if (left == RBT->NIL)
{
fixupNode = right;
transPlant(RBT, node, right);
}
// child 1 : 오른쪽노드 없는 경우
else if (right == RBT->NIL)
{
fixupNode = left;
transPlant(RBT, node, left);
}
// child 2 : 자식노드 2개인 경우 -> successor를 삭제하는 것으로 가정
else
{
successor = findSuccessor(RBT, right);
nColor = successor->color;
fixupNode = successor->right;
// fixupNode를 successor의 자리에 이식
transPlant(RBT, successor, fixupNode);
successor->right = node->right;
successor->right->parent = successor;
// successor를 node의 자리에 이식
transPlant(RBT, node, successor);
successor->left = node->left;
successor->left->parent = successor;
successor->color = node->color;
}
// 삭제 노드의 색이 BLACK인 경우 Violation 발생
if (nColor == BLACK)
{
treeDelFixUp(RBT, fixupNode);
}
// 메모리 영역 해방시켜줌
free(node);
return;
}
