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AVLtree.cpp
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183 lines (170 loc) · 4.36 KB
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#include"AVLtree.h"
AVL::treenode* AVL::find(int val)
{
if (nodecount == 0) return nullptr;
treenode* temp = root;
while (temp->value != val)
{
while (temp != nullptr && temp->value > val) temp = temp->left;
while (temp != nullptr && temp->value < val) temp = temp->right;
if (temp == nullptr) return nullptr;
}
return temp;
}
void AVL::clearall(treenode* node)
{
if (node == nullptr) return;
clearall(node->left);
clearall(node->right);
delete node;
}
void AVL::print(treenode* node)
{
if (node == nullptr) return;
print(node->left);
std::cout << node->value << " ";
print(node->right);
}
/* LL(insert into leftchild's leftsubtree of k1):
sigle rotate
k1 k2
/ \ / \
k2 A B K1
/ \ ==> / / \
B C D C A
/
D
*/
AVL::treenode* AVL::LLrotate(treenode* k1)
{
treenode* k2 = k1->left;
k1->left = k2->right;
k2->right = k1;
k1->height = max(getheight(k1->left), getheight(k1->right)) + 1;
k2->height = max(getheight(k2->left), getheight(k2->right)) + 1;
return k2;
}
/* RR(insert into rightchild's rightsubtree of k1):
sigle rotate
k1 k2
/ \ / \
A k2 k1 C
/ \ ==> / \ \
B C A B D
\
D
*/
AVL::treenode* AVL::RRrotate(treenode* k1)
{
treenode* k2 = k1->right;
k1->right = k2->left;
k2->left = k1;
k1->height = max(getheight(k1->left), getheight(k1->right)) + 1;
k2->height = max(getheight(k2->left), getheight(k2->right)) + 1;
return k2;
}
/* LR(insert into leftchild's rightsubtree of k1):
double rotate
k1 k1 k3
/ \ / \ / \
k2 A k3 A k2 k1
/ \ ==> / ==> / \ \
B k3 k2 B C A
/ / \
C B C
*/
AVL::treenode* AVL::LRrotate(treenode* k1)
{
k1->left = RRrotate(k1->left);
return LLrotate(k1);
}
/* RL(insert into rightchild's leftsubtree of k1):
double rotate
k1 k1 k3
/ \ / \ / \
A k2 A k3 k1 k2
/ \ ==> / \ ==> / / \
k3 B C k2 A C B
/ \
C B
*/
AVL::treenode* AVL::RLrotate(treenode* k1)
{
k1->right = LLrotate(k1->right);
return RRrotate(k1);
}
AVL::treenode* AVL::inserthelp(treenode*& node, int val)
{
if (nodecount == 0) {
root->value = val;
return root;
}
if (node == nullptr)
return (node = new treenode(val, 0));
else if (node->value > val)
node->left = inserthelp(node->left, val);
else
node->right = inserthelp(node->right, val);
node->height = max(getheight(node->left), getheight(node->right)) + 1;
if (getheight(node->left) - getheight(node->right) == 2)
{
if (val < node->left->value)
node = LLrotate(node);
else
node = LRrotate(node);
}
else if (getheight(node->right) - getheight(node->left) == 2)
{
if (val < node->right->value)
node = RLrotate(node);
else
node = RRrotate(node);
}
return node;
}
AVL::treenode* AVL::removehelp(treenode*& node, int val)
{
if (node == nullptr)
{
std::cout << "can't find " << val << std::endl;
return nullptr;
}
if (node->value == val)
{
if (node->right == nullptr)
{
treenode* temp = node;
node = node->left;
delete temp;
return root;
}
else
{
treenode* temp = node->right;
while (temp->left)
temp = temp->left;
node->value = temp->value;
node->right = removehelp(node->right, temp->value);
}
}
else if (node->value > val)
return removehelp(node->left, val);
else
return removehelp(node->right, val);
node->height = max(getheight(node->left), getheight(node->right)) + 1;
if (getheight(node->left) - getheight(node->right) == 2)
{
if (val < node->left->value)
node = LLrotate(node);
else
node = LRrotate(node);
}
else if (getheight(node->right) - getheight(node->left) == 2)
{
if (val < node->right->value)
node = RLrotate(node);
else
node = RRrotate(node);
}
return node;
}