// Remove key from pp. Returns true if pp needs rebalancing. false if not
bool TreeSetImpl::nodeDelete(TreeSetNode *&pp, const void *key) {
TreeSetNode *p = pp;
if(p == NULL) {
return false; // key not found
}
const int c = m_comparator->cmp(p->m_key, key);
if(c > 0) { // pp.key > key. Continue search in left subtree
if(nodeDelete(p->m_left, key)) {
return balanceL(pp);
} else {
return false;
}
}
if(c < 0) { // pp.key < key. Continue search in right subtree
if(nodeDelete(p->m_right, key)) {
return balanceR(pp);
} else {
return false;
}
}
bool result = false;
if(p->m_right == NULL) {
pp = p->m_left;
result = true;
} else if(p->m_left == NULL) {
pp = p->m_right;
result = true;
} else {
m_deleteHelper = p;
if(nodeDel(p->m_left)) {
result = balanceL(pp);
}
p = m_deleteHelper;
}
deleteNode(p);
m_size--;
m_updateCount++;
return result;
}
/*
* Trie deletion has 3 cases
*
* Case 1: The word is a separate branch in the tree and it doesn't have
* any other children. Simply delete the starting node.
* Case 2: The word contains suffices. Only remove the "word" marker
* Case 3: The reverse of Case 2. The word is a suffix. Delete only the
* suffix
*
* This only replaces the deleted node with NULL and then calling the
* sortChild() function and then realloc()
*
* realloc() only fails if size == 0 or if the block cannot be reallocated
*/
void deleteWord(Trie trie, char *str) {
Node current = trie->dummy, temp = NULL;
int i, tmp;
if(!searchWord(trie, str)) return;
/* Test for case 1*/
if(testCase(trie, str, case1)) {
/* Simply remove the node */
i = findChildID(current, str[0]);
nodeDelete(current->child[i]);
resizeChildren(current);
} else if(testCase(trie, str, case2)) { /* Test for case 2 */
/* No real deletion occurs here, the nodes would
* still be there, but it makes the word unsearchable
*/
for(i = 0; i < strlen(str); i++) {
current = findChild(current, str[i]);
}
current->endMarker = false;
} else if(testCase(trie, str, case3)) { /* Test for case 3 */
/* Traverse the word and keep track on which node
* had children > 1, then find the next matching node
* and delete it
*/
temp = trie->dummy;
for(i = 0; i < strlen(str); i++) {
temp = findChild(temp, str[i]);
if(temp->children > 1) {
current = temp;
tmp = i+1;
}
}
i = findChildID(current, str[tmp]);
nodeDelete(current->child[i]);
resizeChildren(current);
}
}
Node* AvlTree::nodeDelete(Node *rootNode, int data){
if (rootNode == NULL){
return NULL;
}
if (data == rootNode->data){
delete rootNode;
return NULL;
}
if (data < rootNode -> data){
rootNode -> left = this -> nodeDelete(rootNode->left, data);
rootNode -> height = MAX(Height(rootNode->left) , Height(rootNode -> right)) + 1;
int rightHeight = 0;
if (rootNode -> right != NULL){
rightHeight = rootNode -> right -> height;
}
if (Height(rootNode -> left) >= rightHeight + 2){
if (data < rootNode -> left -> data){
rootNode = LL(rootNode);
}else{
rootNode = LR(rootNode);
}
}
}else{
if (data > rootNode -> data){
rootNode -> right = nodeDelete(rootNode -> right, data);
rootNode -> height = 1 + MAX(Height(rootNode -> left) , Height(rootNode -> right));
int leftHeight = 0;
if (rootNode -> left != NULL){
leftHeight = rootNode -> left -> height;
}
if (Height(rootNode -> right) >= leftHeight + 2){
if (data > rootNode -> right -> data){
rootNode = RR(rootNode);
}else{
rootNode = RL(rootNode);
}
}
}
}
rootNode -> height = MAX(Height(rootNode -> left) , Height(rootNode -> right)) + 1;
return rootNode;
}
bool TreeSetImpl::remove(const void *key) {
const size_t size = m_size;
nodeDelete(m_root, key);
return size != m_size;
}
void deleteTrie(Trie trie) {
nodeDelete(trie->dummy);
free(trie);
}