不带头结点的链表的增删改查

  1 #include<stdio.h>
  2 #include<malloc.h>
  3 typedef char ElemType;
  4 typedef struct node
  5 {
  6     ElemType data;
  7     struct node *next;
  8 }NHLink;
  9 
 10 //创建单链表 头插
 11 void Create(NHLink **nhead)
 12 {
 13     ElemType x;
 14     while (1)
 15     {
 16         scanf_s("%c", &x);
 17         if (x != ‘*‘)
 18         {
 19             NHLink *p = (NHLink *)malloc(sizeof(ElemType)*sizeof(NHLink));
 20             p->data = x;
 21             p->next = NULL;
 22             if (*nhead == NULL)
 23             {
 24                 *nhead = p;
 25             }
 26             else
 27             {
 28                 //头插
 29                 p->next = *nhead;
 30                 *nhead = p;
 31             }
 32         }
 33         else
 34         {
 35             break;
 36         }
 37     }
 38 }
 39 //查找 按值查找
 40 int Search(NHLink **nhead, ElemType x)
 41 {
 42     NHLink *p = *nhead;
 43     int index = 1;
 44     while (p)
 45     {
 46         if (p->data == x)
 47         {
 48             return index;
 49         }
 50         p = p->next;
 51         index++;
 52     }
 53     return 0;
 54 }
 55 //按下标查找
 56 NHLink *Find(NHLink **nhead, int index)
 57 {
 58     if (index <= 0)
 59     {
 60         return NULL;
 61     }
 62     NHLink *p = *nhead;
 63     int i = 1;
 64     while (p && i != index)
 65     {
 66         p = p->next;
 67         i++;
 68     }
 69     while (p != NULL)
 70     {
 71         return p;
 72     }
 73 }
 74 //(2)删除中间节点（不是第一个也不是最后一个）
 75 void Delete(NHLink **nhead, NHLink *p)
 76 {
 77     NHLink *pNext = p->next;
 78     if (p->next != NULL)
 79     {
 80         p->next = pNext->next;
 81         p->data = pNext->data;
 82         delete pNext;
 83         pNext = NULL;
 84     }
 85     else                //删除为尾节点时，就需要从头遍历链表
 86     {
 87         pNext = (*nhead)->next;
 88         while ((pNext->next != NULL) && (pNext->next != p))
 89         {
 90             pNext = pNext->next;
 91         }
 92         if (pNext->next != NULL)
 93         {
 94             pNext->next = pNext->next->next;
 95             delete p;
 96             p = NULL;
 97         }
 98     }
 99 }
100 //插入 尾插
101 void InsertTail(NHLink **head, ElemType x)
102 {
103     NHLink *p = (NHLink *)malloc(sizeof(ElemType)*sizeof(NHLink));
104     p->data = x;
105     p->next = NULL;
106     if (*head == NULL)
107     {
108         *head = p;
109     }
110     else
111     {
112         while ((*head)->next)
113         {
114             *head = (*head)->next;
115         }
116         (*head)->next = p;
117     }
118 }
119 //插入 头插
120 void InsertHead(NHLink **head, ElemType x)
121 {
122     NHLink *p = (NHLink *)malloc(sizeof(ElemType)*sizeof(NHLink));
123     p->data = x;
124     p->next = NULL;
125     p->next = *head;
126     *head = p;
127 }
128 void Show(NHLink *nhead)
129 {
130     NHLink *p = nhead;
131     while (p)
132     {
133         printf("%c ", p->data);
134         p = p->next;
135     }
136     printf("\n");
137 }
138 int main()
139 {
140     NHLink *nhead = NULL;
141     Create(&nhead);
142     Show(nhead);
143         //按值查找
144     int index = Search(&nhead, ‘c‘);
145     if (index == 0)
146     {
147         printf("未找到该节点！\n");
148     }
149     else
150         printf("%d\n", index);
151     
152     //按下标查找
153     NHLink *p = Find(&nhead, 4);
154     if (p == NULL)
155         printf("查找范围不合法！\n");
156     else
157         printf("%c\n", p->data);
158     //（2）删除某一节点
159     Delete(&nhead, p);
160     Show(nhead);
161     //插入
162         InsertTail(&nhead,‘x‘);
163         Show(nhead);
164         return 0;
165 }