//前序
//用廣度搜索
template <class T>
void AVLTree<T>::preOrder(AVLTreeNode* tree) const
{
/*************遞歸形式走*/
//if (nullptr != tree)
//{
// cout << tree->key << " ";
// preOrder(tree->left);
// preOrder(tree->right);
//}
if (tree == nullptr) {
return;
}
std::queue<AVLTreeNode*>que;
que.push(tree);
while (!que.empty()) {
AVLTreeNode* temp = que.front();
std::cout << temp->key << std::endl;
que.pop();
if (temp->left != nullptr){
que.push(temp->left);
}
if (temp->right != nullptr){
que.emplace(temp->right);
}
}
}
//中序遍歷
//用深度搜索,層次遍歷
template <class T>
void AVLTree<T>::inOrder(AVLTreeNode* tree) const
{
//遞歸形式
//if (nullptr != tree)
//{
// inOrder(tree->left);
// cout << tree->key << " ";
// inOrder(tree->right);
//}
if (tree== nullptr){
return;
}
std::stack<AVLTreeNode*>stacks;
//保存父節點先
while (tree != nullptr || !stacks.empty()){
if (tree != nullptr){
stacks.emplace(tree);
tree = tree->left;
}else {
AVLTreeNode* ptr = stacks.top();
std::cout << ptr->key << std::endl;
stacks.pop();
tree = ptr->right;
}
}
}
//深度搜索,後序遍歷
template <class T>
void AVLTree<T>::postOrder(AVLTreeNode* tree) const
{
//遞歸的方式遍歷
//if (nullptr != tree)
//{
// postOrder(tree->left);
// postOrder(tree->right);
// cout << tree->key << " ";
//}
if (tree == nullptr){
return;
}
std::stack<AVLTreeNode*>stacks1;
stacks1.emplace(tree);
std::stack<AVLTreeNode*>stacks2;
while (!stacks1.empty()){
AVLTreeNode* tmp = stacks1.top();
stacks1.pop();
stacks2.emplace(tmp);
if (tmp->left != nullptr){
stacks1.emplace(tmp->left);
}
if (tmp->right){
stacks1.emplace(tmp->right);
}
}
while (!stacks2.empty()){
AVLTreeNode* tmp = stacks2.top();
stacks2.pop();
std::cout << tmp->key << std::endl;
}
}
//非遞歸查找
template <class T>
typename AVLTree<T>::iterative_search(AVLTreeNode* root, T key) const
{
while (root != nullptr && key != root->key) {
//如果查找小於當前值,就往左邊查找
if (key < root->key) {
root = root->left;
continue;
}
//如果查找值大於當前值,就往右邊查找
if (key > root->key) {
root = root->right;
continue;
}
}
return root;
}
// 銷燬AVL樹
//可以用廣度搜索銷燬樹
template <class T>
void AVLTree<T>::destroy(AVLTreeNode*& tree)
{
if (tree == nullptr) {
return;
}
std::queue<AVLTreeNode*>que;
que.emplace(tree);
while (!que.empty()){
tree = que.front();
que.pop();
if (tree->left != nullptr){
que.emplace(tree->left);
}
if (tree->right != nullptr){
que.emplace(tree->right);
}
tree->left = nullptr;
tree->right = nullptr;
delete tree;
tree = nullptr;
}
}