[英]AVL Trees and Doubly Linked Lists
因此,我真的是編程新手,我現在正在學習一個c ++類,其中我需要編寫和實現AVL樹,並使用雙向鏈接列表逐級打印樹的內容。 老師真的很挑剔,所以我們不能使用標准庫中的任何容器。 我的雙向鏈接列表應該工作正常,因為我在以前的項目中使用了它,但是在嘗試將其與AVL樹結合使用時出現錯誤。 我知道我的代碼可能有很多需要修改的東西,但是一次只能修改一個。 我收到以下錯誤,因此我想知道你們是否可以幫助我找出解決方法。 另外,如果您對如何改進我的代碼有任何建議,我將不勝感激。
在'void AVLTreeSet :: print(std :: ofstream&)的實例中[使用ItemType = std :: basic_string; std :: ofstream = std :: basic_ofstream]':Lab6 / main.cpp:80:20:從此處需要Lab6 / AVLTreeSet.h:152:49:錯誤:無法轉換'LinkedList> :: AVLNode *> :: Node *'到初始化AVLNode *中的'AVLTreeSet> :: AVLNode *'n = MyList.remove(i);
這是我的AVLTree.h:
#pragma once
#include <fstream>
#include "LinkedList.h"
using namespace std;
template <typename ItemType>
class AVLTreeSet {
struct AVLNode {
ItemType item;
int height;
AVLNode* left;
AVLNode* right;
AVLNode(const ItemType& _item, AVLNode* _left = NULL, AVLNode* _right = NULL, int _height = 0) :
item(_item), left(_left), right(_right), height(_height) {}
};
AVLNode* root;
int size = 0;
public:
void RemoveBelowRoot(AVLNode *& n, const ItemType& item)
{
if (n == NULL)
{
return;
}
else if(item < n->item)
{
RemoveBelowRoot(n->left, item);
}
else if(item > n->item)
{
RemoveBelowRoot(n->right, item);
}
else if(n->left == NULL)
{
n = n->right;
}
else if (n->right == NULL)
{
n = n->left;
}
else
{
n = findMin(n->right);
RemoveBelowRoot(n->right, n->item);
}
balance(n);
size--;
// update height of nodes on this path
}
AVLNode * findMin(AVLNode* n)
{
if (n == NULL)
{
return n;
}
else if (n->left->item < n->item)
{
findMin(n->left);
}
else if(n->left->item > n->item)
{
findMin(n->right);
}
return n;
}
void remove(const ItemType& item) {
RemoveBelowRoot(root, item);
}
bool find(const ItemType& item) {
if (findBelowRoot(root, item))
{
return true;
}
return false;
}
bool findBelowRoot(AVLNode * n, const ItemType& data)
{
if (n->item == data)
{
return true;
}
else if (data > n->item)
{
findBelowRoot(n->right, data);
}
else if (data < n->item)
{
findBelowRoot(n->left, data);
}
}
void clear()
{
while (getHeight(root) != 0)
{
// remove
}
}
void addBelowRoot(AVLNode *& n, const ItemType& item)
{
if (n == NULL)
{
n = new AVLNode(item);
size++;
}
else if (item < n->item)
{
addBelowRoot(n->left, item);
}
else if(item > n->item)
{
addBelowRoot(n->right, item);
}
}
void add(const ItemType& item) {
addBelowRoot(root, item);
}
void print (ofstream& out)
{
if (root == NULL)
{
return;
}
else {
LinkedList<AVLNode *> MyList;
MyList.insert(0, root); // add root to Q
while (MyList.getSize() != 0) // While Q is not empty
//(figure out how many items are in that level)(levelsize = Q.size();)
{
for (auto i = 0; i < MyList.getSize(); i++) // for (int 1 = 0; i < LEVELSIZE; i++)
{
AVLNode* n = MyList.remove(i);
out << "level " << i << " " << n->item << "(" << n->height << ") ";
if (n->left != NULL) {
MyList.insert(MyList.getSize(), n->left);
}
if (n->right != NULL) {
MyList.insert(MyList.getSize(), n->right);
}
}
}
out << "\n ";
}
}
void balance (AVLNode *n)
{
if (getHeight(n->left) - getHeight(n->right))
{
balanceToRight(n);
}
if (getHeight(n->right) - getHeight(n->left))
{
balanceToLeft(n);
}
}
int getHeight(AVLNode *& n)
{
if (n == NULL)
{
return 0;
}
else
{
return n->height;
}
}
void balanceToRight(AVLNode * n)
{
if (getHeight(n->left->right) > getHeight(n->left->left))
{
rotateLeft(n->left);
}
rotateRight(n);
}
void rotateRight(AVLNode *&n)
{
AVLNode * k = n->left;
n->left = k->right;
k->right = n;
n = k;
// update heights of k and n
}
void rotateLeft(AVLNode *& n)
{
AVLNode * k = n->right;
n->right = k->left;
k->left = n;
n = k;
// update heights of k and n
}
void balanceToLeft(AVLNode * n)
{
if (getHeight(n->right->left) > getHeight(n->right->right)) // check with TAs if this is right
{
rotateRight(n);
}
rotateLeft(n);
}
/*void updateHeight(AVLNode *& n)
{
}*/
};
現在這是我的LinkedList.h
#pragma once
#include <iostream>
#include <cstddef>
#include <fstream>
using namespace std;
template <typename ItemType>
class LinkedList {
struct Node {
ItemType item;
Node *next;
Node *prev;
Node(const ItemType &_item, Node *_next = NULL, Node *_prev = NULL) :
item(_item), next(_next), prev(_prev) { }
};
Node *head;
Node *tail;
int size = 0;
public:
~LinkedList()
{
clear();
}
void insert(int index, ItemType& item) {
if (index > size || size < 0)
{
return;
}
Node * newNode = new Node(item);
if (size == 0)
{
head = newNode;
tail = newNode;
newNode->next = NULL;
newNode->prev = NULL;
size++;
}
else if (index == 0)
{
head->prev = newNode;
newNode->next = head;
head = newNode;
size++;
}
else if (index == size) //INSERTING AT THE END
{
newNode->prev = tail;
newNode->next = NULL;
tail->next = newNode;
tail = newNode;
size++;
}
else {
Node* n = find_node(index);
newNode->next = n;
newNode->prev = n->prev;
n->prev->next = newNode;
n->prev = newNode;
size++;
}
}
Node * remove(int index) {
if (head == NULL || index >= size || index < 0)
{
return NULL;
}
else {
Node* name = find_node(index);
Node * n;
if (size == 1) // REMOVE THE ONLY NODE
{
n = head;
head = NULL;
tail = NULL;
size--;
}
else if (index == 0) //REMOVE THE FIRST NODE WHEN THERE'S MORE THAN ONE IN THE LIST
{
n = head;
head = head->next;
head->prev = NULL;
size--;
}
else if (index == size-1) //REMOVE THE LAST WHEN THERE'S MORE THAN ONE NODE IN THE LIST
{
n = tail;
tail = n->prev;
tail->next = NULL;
size--;
}
else
{
n = find_node(index);
n->prev->next = n->next;
n->next->prev = n->prev;
size--;
}
delete n;
return name;
}
}
Node * find_node(int index)
{
Node * n = NULL;
if (0 <= index && index <= size/2)
{
n = head;
for (int i = 0; i < index; i++)
{
n = n->next;
}
}
else if (size/2 < index && index <= size-1)
{
n = tail;
for (unsigned i = size-1; i > index; i--)
{
n = n->prev;
}
}
return n;
}
int getSize()
{
return size;
}
/* void print(LinkedList <string>& list, ofstream& out, int i)
{
if(head == NULL)
{
return;
}
out << "node " << i << ": " << getItem(i) << "\n";
}
Node* getItem(const int index)
{
if (index > size)
{
return NULL;
}
Node* temp = head;
for (unsigned i = 0; i < size; i++)
{
if (i == index)
{
return temp;
}
temp = temp-> next;
}
return NULL;
}*/
/* int find(const ItemType& item) {
Node * NodeP = head;
for (unsigned i = 0; i < size; i++)
{
if (NodeP->item == item)
{
return i;
}
NodeP = NodeP->next;
}
return -1;
}*/
void clear()
{
while (size != 0){
remove(0);
}
}
};
非常感謝!
LinkedList::remove
返回LinkedList::Node
指針。 您正在嘗試將其分配給AVLTreeSet::AVLNode
指針。
您要查找的AVLTreeSet::AVLNode *
在返回的Node
指針的item
成員中。
您可以執行以下操作:
LinkedList<AVLNode *>::Node* n = MyList.remove(i);
AVLNode *treeNode = n->item;
筆記
remove
的返回值。 remove
實際上delete
該節點然后返回它。 然后,您正在訪問已刪除的內容,即未定義行為。 在進一步操作之前,您確實需要解決此問題。 for
循環只會刪除大約一半的對象,因為您正在從列表中刪除項目,同時仍使用i
沿列表進一步迭代。
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