数据结构：链表插入和删除算法的演示

  1 # include <stdio.h>
  2 # include <malloc.h>
  3 # include <stdlib.h>
  4 
  5 typedef struct Node  //要理解typedef的用法
  6 {
  7     int data;
  8     struct Node * pNext;
  9 }NODE, * PNODE;
 10 PNODE creat(void);
 11 void traverse(PNODE pHead);   //注意函数的返回值类型
 12 bool empty(PNODE pHead);
 13 int length(PNODE);
 14 bool insert(PNODE, int, int);
 15 bool delet(PNODE, int, int *);
 16 void sort(PNODE);
 17 
 18 int main(void)
 19 {
 20     PNODE pHead = NULL;
 21     int len;
 22     int val;
 23     pHead = creat();
 24     traverse(pHead);
 25     if(empty(pHead))
 26         printf("空\n");
 27     else 
 28         printf("不空\n");
 29     len = length(pHead);
 30     printf("链表的长度是%d\n",len);
 31     sort(pHead);
 32     traverse(pHead);
 33     insert(pHead,3,31);
 34     traverse(pHead);
 35     if(delet(pHead,3,&val))
 36     {
 37         printf("删除成功，您删除的元素为：%d!\n",val);
 38     }
 39     else
 40     {
 41         printf("删除失败~");
 42     }
 43     traverse(pHead);
 44 
 45     return 0;
 46 
 47 }
 48 PNODE creat(void)
 49 {
 50     int len;
 51     int i;
 52     int val;
 53     PNODE pHead = (PNODE)malloc(sizeof(NODE));
 54     if(NULL == pHead)
 55     {
 56         printf("分配失败，程序终止");
 57         exit(-1);
 58     }
 59     PNODE pTail = pHead;
 60     pTail->pNext = NULL; 
 61     printf("请输入链表节点长度：len= ");
 62     scanf("%d",&len);
 63     for(i=0;i<len;i++)
 64     {
 65         printf("请输入第%d个值",i+1);
 66         scanf("%d",&val);
 67         PNODE pNew = (PNODE)malloc(sizeof(NODE));
 68         
 69             if(NULL == pNew)
 70             {
 71                 printf("分配失败，程序终止");
 72                 exit(-1);
 73             }
 74         pNew->data = val;
 75         pTail->pNext = pNew;
 76         pNew->pNext= NULL;
 77         pTail = pNew;    //算法要理解，可借助图形加上理解
 78 
 79     }
 80     return pHead; // 返回值
 81     
 82 }
 83 
 84 void traverse(PNODE pHead)//遍历
 85 {
 86     PNODE p = pHead->pNext;
 87 
 88     while(NULL != p)
 89     {
 90         printf("%d ",p->data);
 91         p = p->pNext;   //移到下一个节点
 92             
 93     }
 94     printf("\n");
 95 
 96 }
 97 bool empty(PNODE pHead) //判断是否为空
 98 {
 99     if(NULL == pHead->pNext)
100         return true;
101     else
102         return false;
103 }
104 int length(PNODE pHead)
105 {
106     PNODE p = pHead->pNext;
107     int len = 0;
108 
109     while(NULL != p)
110     {
111         ++len;
112         p = p->pNext;
113     }
114     return len;
115 
116 }
117 void sort(PNODE pHead)//排序
118 {
119     int i,j,t;
120     int len;
121     PNODE p,q;
122     len = length(pHead);
123     for(i=0,p=pHead->pNext ;i<len-1;i++ ,p=p->pNext)
124     {
125         for(j=i+1,q=p->pNext;j<len;j++,q=q->pNext)
126         {
127             if(q->data > p->data)
128             {
129             t = q->data;
130             q->data = p->data;
131             p->data=t;
132             }
133 
134         }
135     }
136     return;
137 }
138 bool insert(PNODE pHead, int pos, int val) //插入
139 {
140     int i = 0;
141     PNODE p = pHead;
142 
143     while(NULL != p && i<pos-1)
144     {
145         p = p->pNext;
146         i++;
147     }
148     if(i>pos-1 || NULL==p)
149         return false;
150     PNODE pNew = (PNODE)malloc(sizeof(NODE));
151     if(NULL == pNew)
152     {
153         printf("动态内存分配失败\n");
154         exit(-1);
155     }
156     pNew->data = val;
157     PNODE q=p->pNext;
158     p->pNext = pNew;
159     pNew->pNext=q;
160     
161     return true;
162 }
163 bool delet(PNODE pHead, int pos, int * pVal)//删除
164 {
165     int i = 0;
166     PNODE p = pHead;
167 
168     while(NULL != p->pNext && i<pos-1)
169     {
170         p = p->pNext;
171         i++;
172     }
173     if(i>pos-1 || NULL==p->pNext)
174         return false;
175     PNODE q = p->pNext;
176     *pVal = q->data;
177     p->pNext = p->pNext->pNext;
178     free(q);
179     q=NULL;
180     return true;
181 
182 }
183 /*
184 =============================
185 请输入链表节点长度：len= 4
186 请输入第1个值23
187 请输入第2个值54
188 请输入第3个值12
189 请输入第4个值33
190 23 54 12 33
191 不空
192 链表的长度是4
193 54 33 23 12
194 54 33 31 23 12
195 删除成功，您删除的元素为：31!
196 54 33 23 12
197 Press any key to continue
198 =============================
199 */