(C/C++) Link List - C++ 版本

利用C++寫一個基本的 Link list 練習，功能包含 pint list、CreatList、Insert、Delete、Reverse、Search、Clear、GetLen。

先建立相關的Class ListNode、LinkedList

 class LinkedList;  // 需要先宣告
 class ListNode{
 public:
     int data;
     ListNode *next;
 public:
     ListNode():data(), next(){};
     ListNode(int a):data(a), next(){};
     friend class LinkedList;
 };

 class LinkedList{
 public:
     // int size;                // size是用來記錄Linked list的長度, 非必要
     ListNode *first;
 public:
     LinkedList() :first(){};
     void PrintList();
     void CreateList(int *arr, int len);
     void Push_front(int x);
     void Push_back(int x);
     void Delete(int x);
     void Clear();
     void Reverse();
     int ListLen();
     ListNode * ListSearch(int x);
     void Insert(int x, int data);
 };

首先是Creat List，給一個arry利用Link list串在一起。

 void LinkedList::CreateList(int *arr, int len)
 {
     if (arr == NULL || len == )
         return;

     ListNode * previous = new ListNode();
     for (int i = ; i < len; i++)
     {
         ListNode * newNode = new ListNode();
         newNode->data = arr[i];
         if (i == )
             first = newNode;
         else
             previous->next = newNode;
         newNode->next = NULL;
         previous = newNode;
     }
 }

PrintList : 印出所有的 List

 void LinkedList::PrintList()
 {
     if (first == )
     {
         cout << "List is empty.\n";
         return;
     }

     ListNode * current = first;
     while (current != )
     {
         cout << current->data << "  ";
         current = current->next;
     }
     cout << endl;
 }

Insert List : 把新的node插在x之後

 void LinkedList::Insert(int x, int data)
 {
     ListNode * current = first;
     ListNode * previous = new ListNode();
     ListNode * newNode = new ListNode();
     while (current)
     {
         if (current->data == x)
         {
             newNode->data = data;
             previous->next = newNode;
             newNode->next = current;
             break;
         }
         else
         {
             previous = current;
             current = current->next;
         }
     }

 }

Delete : 刪除特定 node

 void LinkedList::Delete(int x)
 {
     ListNode * current = first, *previous = ;

     while (current !=  && current->data != x) {
         previous = current;
         current = current->next;
     }

     if (current == ) {
         std::cout << "There is no " << x << " in list.\n";
     }
     else if (current == first) {
         first = current->next;
         delete current;
         current = ;
     }
     else {
         previous->next = current->next;
         delete current;
         current = ;
     }
 }

Reverse : 反轉 list

 void LinkedList::Reverse()
 {
     if (first ==  || first->next == )
         return;

     ListNode *previous = , *current = first, *preceding = first->next;

     while (preceding != )
     {
         current->next = previous;
         previous = current;
         current = preceding;
         preceding = preceding->next;
     }
     current->next = previous;
     first = current;
 }

Search node : 尋找特定node

 ListNode * LinkedList::ListSearch(int x)
 {
     if (first == )
     {
         printf("List is empty\n");
         return NULL;
     }
     ListNode * newNode = first;
     while (newNode)
     {
         if (newNode->data != x)
             newNode = newNode->next;
         else
             return newNode;
     }
     printf("not found Node!!\n");
     return NULL;
 }

ListLen : 回傳List長度

 int LinkedList::ListLen()
 {
     if (first == )    return NULL;
     int index = ;
     ListNode * newNode = first;
     while (newNode)
     {
         newNode = newNode->next;
         index++;
     }
     return index;
 }

Push_front/back : 插入節點在頭/尾

 void LinkedList::Push_front(int x)
 {
     ListNode *newNode = new ListNode(x);
     newNode->next = first;
     first = newNode;
 }

 void LinkedList::Push_back(int x)
 {
     ListNode * newNode = new ListNode(x);
     if (first == )
     {
         first = newNode;
         return;
     }
     ListNode * current = first;
     while (current->next != )
     {
         current = current->next;
     }
     current->next = newNode;
 }