单链表的实现

单链表是数据结构中重要并且基础的一环，学习数据结构就需要知道单链表有的常用操作。

1> 单链表的头插式创建
2> 单链表的尾插式创建
3>单链表的长度计算
4>单链表的打印输出
5> 单链表的释放操作
6>单链表是否为空判断
7>单链表在指定index插入指定元素
8>单链表删除指定index的节点
9>单链表的逆置
10>两个有序单链表的合并成一个链表 不申请额外空间
11>单链表是否有环判断

/*   linklist.h*/#include <iostream> typedef int DataType; typedef struct Node {   DataType data;   Node*    next; }; typedef Node* LinkList; LinkList HeadCreateLinkList()  // 头插式创建带头链表 {   Node* head  = (Node*) malloc( sizeof(Node));   if (NULL == head)   {     std::cout << "tail create linklist head node and malloc buffer failed ~" << std::endl;     return NULL;   }   int tmp;   head->next = NULL;   std::cout << "Input list elems and -1 end !" << std::endl;   while( std::cin >> tmp )   {     if (-1 == tmp) break ;     Node* node = (Node*) malloc( sizeof(Node));     if (NULL == node){       std::cout << "tail create linklist elem node and malloc buffer failed ~" << std::endl;       exit(0);     }     node->data = tmp;     node->next = head->next;     head->next = node;   }   return head; } LinkList TailCreateLinkList()   // 尾插式创建带头链表 {   Node* head;   Node* curNode;   head = (Node*)malloc( sizeof(Node));   if (head == NULL)   {     std::cout << "create linklist and malloc buffer failed ~" << std::endl;     return NULL;   }   curNode = head;   int tmp;   std::cout << "Input list elems and -1 over!" << std::endl;   while(std::cin >> tmp)   {     if (-1 == tmp) break ;     Node* sptr = (Node*)malloc( sizeof(Node));     if (sptr == NULL)     {       std::cout << "create linklist elems and malloc buffer failed ~" << std::endl;       exit(0);     }     sptr->data = tmp;     curNode->next = sptr;     curNode =sptr;   }     curNode->next = NULL;   return head; } int LinkListLength(LinkList list) // 计算链表长度 不包括头结点 {   int len = -1;   while(NULL != list)   {     len++;     list = list->next;   }   return len; } void PrintLinkList(LinkList list) // 带头节点链表打印 {  if (NULL == list) return;   Node *ptr = list->next;   std::cout << "list elems [" ;   while (NULL != ptr)   {       std::cout << " " << ptr->data;       ptr = ptr->next;   }   std::cout << " ]" << std::endl; } void DestoryLinkList(LinkList list) // 释放带头链表 {   Node* ptr = list;   Node* tmp;     while(ptr)   {     tmp = ptr->next;     free(ptr);     ptr = tmp;   }   std::cout << "LinkList is destory ~" << std::endl; } int Empty(LinkList list)  // 判断链表是否为空 {   return ((list == NULL) || (list->next == NULL)); }int InsertNode(LinkList list, int elem , int index) // 在index节点之前插入节点值为elem的节点 按照index{  int len = LinkListLength(list);  if (index < 1 || index > len)  {    std::cout << "The index out range !" << std::endl;    return 0;  }  Node* cur = list;  for ( int i = 1; i < index; i++) // 找到第index节点的前驱节点  {     cur = cur->next;  }   Node* node = (Node*) malloc( sizeof(Node));  if (!node)  {    std::cout << "malloc memory failed for insert new node ~" << std::endl;    exit(0);  }  node->data = elem;  node->next = cur->next;  cur->next = node;  return 1;}int DeleteNode(LinkList list, int index)  // 按照对应的链表索引进行删除{  int len = LinkListLength(list);  if(index < 1 || index > len)   {     std::cout << "Delete node out of range ~" << std::endl;     return 0;   }  Node* cur = list;  for ( int i = 1; i < index; i++)   // 找到index节点的前驱节点  {    cur = cur->next;  }  Node* tmp = cur->next;  cur->next = cur->next->next;  free(tmp);  return 1;}void ReverseLinkList(LinkList list)   // 单链表逆置{  if (Empty(list) || LinkListLength(list) <= 1)    return;  Node* head = list;  Node* cur = list->next;  Node* next = cur->next;       // next 每次都指向待添加的第一个结点  cur->next = NULL;               // 置空第一个结点   while(next)  {    cur = next;    next = next->next;                    // 往后移动还没有添加的指针    cur->next = head->next;          // 头部插入取到的新节点 新节点指向头结点后的列表    head->next = cur;                    // 头结点指向新节点  }}LinkList MergeLinkList(LinkList listA, LinkList listB)  // 合并两个非升序链表到一个链表 不申请额外空间{  if (listA == NULL || listB == NULL)    return NULL;  LinkList listC = listA;  Node* pa = listA->next;  Node* pb = listB->next;  free(listB);  listC->next = NULL;  Node* pc = listC;  int x = 0;  while(NULL != pa && NULL != pb)  {    if (pa->data < pb->data)    {      pc->next = pa;      pa = pa->next;    } else if (pa->data > pb->data)    {       pc->next = pb;       pb = pb->next;    } else    {      pc->next = pa;      pa = pa->next;      Node* tmp = pb;      pb = pb->next;      free(tmp);      x++;    }    pc = pc->next;  }  if(pa) pc->next = pa;  if(pb) pc->next = pb;  std::cout << "free node :" << x << std::endl;  return listC;}int ExistLoopLinkList(LinkList list)   // 判断单链表是否存在环{  if(NULL == list || list->next == NULL)    return 0;  Node* slow = list;  Node* fast = list;  while(fast && fast->next)  {    fast = fast->next->next;    slow = slow->next;       if (slow == fast)      return 1;  }  return 0;}/*  main.cpp*/#include "linklist.h"int main(){  // test head create linklist  Node* headList = HeadCreateLinkList();  PrintLinkList(headList);  std::cout << "headList length is ：" << LinkListLength(headList) << std::endl;  DestoryLinkList(headList);  // test loop linklist  Node* list = TailCreateLinkList();  if (ExistLoopLinkList(list))    std::cout << "List exist loop ~~~" << std::endl;  else    std::cout << "List not exist loop ~~~" << std::endl;  Node* p = list->next->next;  Node* cur = list;  while(p->next)  {    p = p->next;    cur = cur->next;  }   p->next = cur;   if (ExistLoopLinkList(list))     std::cout << "List exist loop ~~~" << std::endl;   else     std::cout << "List not exist loop ~~~" << std::endl;   DestoryLinkList(list);  // test merge 2 linklist  LinkList listA = TailCreateLinkList();  PrintLinkList(listA);  LinkList listB = TailCreateLinkList();  PrintLinkList(listB);  std::cout << "Merge listA and ListB " ;  LinkList ListC = MergeLinkList(listA, listB);  if (NULL != ListC)  {    PrintLinkList(ListC);  }  DestoryLinkList(ListC);  // test reverse linklist  LinkList tailList = TailCreateLinkList();  PrintLinkList(tailList);  std::cout << "tailList length is ：" << LinkListLength(tailList) << std::endl;  std::cout << "tailList after reverse:" ;  ReverseLinkList(tailList);  PrintLinkList(tailList);  // test insert and delete elems   std::cout << "Input insert elem and index " << std::endl;   int elem, index;   std::cin >> elem >> index;   if (InsertNode(tailList, elem, index))   {     std::cout << "insert successd and after insert elem : " ;     PrintLinkList(tailList);   }     std::cout << "Input Delete index " << std::endl;   std::cin >> index;   if (DeleteNode(tailList, index))   {     std::cout << "delete successd and after delete elem : " ;     PrintLinkList(tailList);   }   DestoryLinkList(tailList);  return 0;}