刚刚学会了双向链表的概念。我实现了它，幸运的是它成功了。但我的问题是当我测试一些测试用例时，这是我的测试用例，
（第1列是命令。第2列是应用命令的索引。第3列是插入的字。命令1是插入，命令2是删除，命令4是设置，命令6是清除，命令7是打印，命令8是退出。）
1 0 this
1 1 would
1 2 be
1 3 cleared
6
1 0 hello
1 1 world
1 1 beautiful
1 2 world
4 2 wonderful
2 1
1 0 what
4 1 a
7
8
似乎是
[what, a, beautiful, wonderful, world]
应该打印
[what, a, wonderful, world].
有人可以帮我解决这个问题吗？
#include<iostream>
#include<cstdlib>
using namespace std;
template <class T>
class Node {
private:
T data;
Node<T> *next;
Node<T> *prev;
public:
Node(T data) {
this->data = data;
this->next = NULL;
this->prev = NULL;
};
void setData(T data) {
this->data = data;
};
T getData() {
return this->data;
};
void setNext(Node *next) {
this->next = next;
};
Node *getNext() {
return this->next;
};
void setPrev(Node *prev) {
this->prev = prev;
};
Node *getPrev() {
return this->prev;
};
};
template <typename T>
class List {
private:
Node<T> *first; // or start or head or something
Node<T> *last; // or end or tail or something
int _size;
public:
List() {
this->first = NULL;
this->last = NULL;
this->_size = 0;
};
~List();
void insert(int index, T data);
T remove(int index);
T get(int index);
void set(int index, T data);
int size();
bool isEmpty();
void clear();
friend ostream &operator <<(ostream &os, const List &list) {
if (list._size == 0) os << "*** List is empty. ***" << endl;
else {
os << "[";
for (Node<T> *i = list.first; i != NULL; i = i->getNext()) {
os << i->getData();
if (i->getNext() != NULL) os << ", ";
else os << "]" << endl;
}
}
return os;
};
};
template <class T>
void List<T>::insert(int index, T data)
{
Node<T> *newNode;
newNode = new Node<T>(data);
Node<T> *temp;
temp = first;
int i = 0;
if (index > size())
{
cout << "Sorry, can't perform this.";
return;
}
if (temp == NULL)
{
this->first = newNode;
this->last = newNode;
this->_size++;
return;
}
if(index == size())
{
while (i < index-1)
{
i++;
temp = temp->getNext();
}
newNode->setData(data);
temp->setNext(newNode);
newNode->setPrev(temp);
newNode->setNext(NULL);
this->last = newNode;
this->_size++;
}
else if (index == 0)
{
this->first = newNode;
newNode->setData(data);
newNode->setPrev(NULL);
newNode->setNext(temp);
temp->setPrev(newNode);
this->_size++;
}
else if (index > 0 && index < size())
{
while (i < index-1)
{
i++;
temp = temp->getNext();
}
newNode->setData(data);
newNode->setPrev(temp);
newNode->setNext(temp->getNext());
temp->setNext(newNode);
temp = temp->getNext();
temp->setPrev(newNode);
this->_size++;
}
}
template <class T>
int List<T>::size()
{
return this->_size;
}
template <class T>
T List<T>::remove(int index)
{
Node<T> *temp = first;
int i = 0;
T value;
if (temp == NULL)
{
cout << "Couldn't perform this.";
return 0;
}
if (temp->getNext() == NULL)
{
value = temp->getData();
delete temp;
this->first = NULL;
this->last = NULL;
_size--;
return value;
}
else if (index == _size - 1)
{
temp = this->last;
this->last = this->last->getPrev();
this->last->setNext(NULL);
value = temp->getData();
delete temp;
_size--;
return value;
}
else if (index == 0)
{
value = this->first->getData();
this->first = this->first->getNext();
this->first->setPrev(NULL);
delete temp;
_size--;
return value;
}
else if (index > 0 && index < size() - 1)
{
Node<T> *temp2 = this->first;
Node<T> *temp3 = this->first;
while (i < index)
{
temp3 = temp3->getNext();
temp2 = temp2->getNext();
temp = temp->getNext();
i++;
}
temp3 = temp3->getNext();
temp2 = temp2->getPrev();
temp2->setNext(temp3);
temp3->setPrev(temp2);
value = temp->getData();
_size--;
return value;
}
}
template <class T>
T List<T>::get(int index)
{
int i = 0;
Node<T> *temp = first;
if(temp == NULL) return "";
if (index > _size) return "";
while (i < index )
{
temp = temp->getNext();
i++;
}
return temp->getData();
}
template <class T>
bool List<T>::isEmpty()
{
if (size() <= 0)
return true;
return false;
}
template <class T>
void List<T>::clear()
{
Node<T> *temp = first;
while (this->first != NULL)
{
_size--;
this->first = this->first->getNext();
delete temp;
temp = first;
}
this->last = NULL;
}
template <class T>
void List<T>::set(int index, T data)
{
Node<T> *temp = first;
if (temp == NULL)
{
cout << "Couldn't perform this.\n";
return;
}
int i = 0;
while (i < index)
{
temp = temp->getNext();
i++;
}
temp->setData(data);
return;
}
template <class T>
List<T>::~List()
{
cout << "Bye";
}
int main()
{
List <string> lists;
int index, prompt;
string data;
while (prompt != 8)
{
cout << "\n(1) Insert (index, data)\n(2) Remove (index)\n(3) Get (index)\n(4) Set (index, data)\n(5) Size\n(6) Clear\n(7) Show\n(8) Exit";
cout << "\nEnter number: ";
cin >> prompt;
if (prompt == 1)
{
cout << "Insert (index, data): ";
cin >> index;
cin >> data;
lists.insert(index, data);
}
else if (prompt == 2)
{
cout << "Enter index: ";
cin >> index;
lists.remove(index);
}
else if (prompt == 3)
{
cout << "Enter index: ";
cin >> index;
if (lists.get(index) == "")
{
cout << "Very impossible.";
}
else cout << lists.get(index) << endl;
}
else if (prompt == 4)
{
cout << "Set (index, data): ";
cin >> index;
cin >> data;
lists.set(index, data);
}
else if (prompt == 5)
{
cout << lists.size();
}
else if (prompt == 6)
{
lists.clear();
}
else if (prompt == 7)
{
cout << lists;
}
else
{
exit(1);
}
}
}
答案 0 :(得分：1)
List::remove()
如果我更改了行：
Node<T> *temp2 = this->first;
Node<T> *temp3 = this->first;
由：
Node<T> *temp2 = this->first;
Node<T> *temp3 = temp2->getNext();
一切都对我有用。