(已解決)c++ 作業想不懂... - 伊莉討論區

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#include <iostream>
#include <iomanip>
using namespace std;
class Node
{
public:
int data;
Node *nextNode, *preNode;
};
class List
{
public:
Node *head,*tail, *now;
List(){head = tail = NULL;}
void insert(int data);
void show();
void remove(int data);
void reverseShow();
};
void List::insert(int data)
{
Node *newnode = new Node; //建立 newnode
newnode->data = data; //指定data 給newnode->data
newnode->nextNode = newnode->preNode = NULL; //將newnode的nextNode與preNode指向NULL
//如果head為NULL,表示當前這個 newnode 將成為為List中第一個Node, 所以當前這個 newnode 既是頭也是尾
if (head ==NULL)
head = tail = newnode; //將head與tail指向這個newnode
//如果head不是NULL, 表示List中已有Node, 將List中最後一個node的nextNode指向 newnode,
//將 newnode 的preNode指向List中原本最後一個Node
else
{
tail->nextNode = newnode;
newnode->preNode =tail;
tail = newnode; //因為newnode加入後成為最後一個node, 所以將tail指向newnode
}
}
void List::show()
{
Node *n;
for(n = head; n!=NULL; n=n->nextNode)
{
cout<<n->data<<setw(4);
}
cout<<"\n";
}
void List::reverseShow()
{
Node *n;
for(n=tail; n!=NULL; n=n->preNode)
{
cout<<n->data<<setw(4);
}
cout<<"\n";
}
void List::remove(int data)
{
Node *n;
if (head==NULL)
{
cout<<"Can not remove data because the list is already empty !"<<endl;
}
else if(head==tail&&head->data==data)
{
n=head;
head=tail=NULL;
delete n;
}
else
{
for(n = head; n!=NULL; n=n->nextNode)
{
if(n->data==data)
{
if (n==head)
{
head=n->nextNode;
head->preNode=NULL;
}else if (n==tail)
{
tail=n->preNode;
tail->nextNode=NULL;
}else
{
n->preNode->nextNode = n->nextNode;
n->nextNode->preNode=n->preNode;
}
delete n;
break;
}
}
}
}
void main()
{
List aa;
aa.insert(10);
aa.insert(11);
aa.insert(12);
aa.insert(13);
aa.show();
aa.remove(10);
aa.reverseShow();
aa.remove(13);
aa.show();
aa.insert(15);
aa.reverseShow();
system("Pause");
}

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