數據結構-雙向鏈表的創建、插入和刪除
雙向鏈表是數據結構中重要的結構，也是線性結構中常用的數據結構，雙向指針，方便用戶從首結點開始沿指針鏈向后依次遍歷每一個結點，結點的前驅和后繼查找方便。
#include <stdio.h>
#include <stdlib.h>
//雙向鏈表結點的定義
typedef struct dbnode
{
int data;
struct dbnode *prio, *next;
}DbNode, linkdblist;
//創建雙向鏈表
DbNode *creatlist(void)
{
linkdblist *p, *q, *head;
q = p = (linkdblist *)malloc(sizeof(linkdblist));
p->next = NULL;
head = q;
p = (linkdblist *)malloc(sizeof(linkdblist));
scanf("%d", &p->data);
while (p->data != -1)
{
q->next = p;
p->prio = q;
q = p;
p = (linkdblist *)malloc(sizeof(linkdblist));
scanf("%d", &p->data);
}
q->next = NULL;
return head;
}
//輸出雙向鏈表
void print(linkdblist *head)
{
linkdblist *p;
p = head->next;
if (p == NULL)
printf("空鏈表！\n");
while (p != NULL)
{
printf("%d ", p->data);
p = p->next;
}
}
//向雙向鏈表中的第i個位置插入一個結點x
void insertdblist(linkdblist *head, int x, int i)
{
linkdblist *p, *q = head;
if (i == 1)
q = head;
else
{
q = q->next;
int c = 1;
while ((c<i - 1) && (q != NULL))
{
q = q->next;
c++;
}
}
if (q != NULL && q->next != NULL)
{
p = (linkdblist *)malloc(sizeof(linkdblist));
p->data = x;
p->prio = q;
p->next = q->next;
q->next = p;
q->next->prio = p;
}
else
printf("找不到插入的位置！");
}
//刪除雙向鏈表中指定位置上的一個結點
void deletelinkdblist(linkdblist *head, int i)
{
linkdblist *p, *q = head;
if (i == 1)
q = head;
else
{
q = q->next;
int c = 1;
while (c < i - 1 && q != NULL)
{
q = q->next;
c++;
}
}
if (q != NULL && q->next != NULL)
{
p = q->next;
p->prio = q;
p->prio->next = p->next;
p->next->prio = p->prio;
free(p);
}
else if (q->next == NULL)
{
p = q;
p->prio->next = NULL;
free(p);
}
else
printf("沒有找到待刪除的結點");
}
//雙向鏈表的主函數
void main()
{
linkdblist *head;
head = creatlist();
print(head);
printf("\n\n====向雙向鏈表的某位置插入一個值====\n");
int num, i;
printf("輸入插入的位置：");
scanf("%d", &i);
printf("\n輸入插入的值：");
scanf("%d", &num);
insertdblist(head, num, i);
print(head);
printf("\n");
printf("\n\n====刪除雙向鏈表的某位置上的一個值====\n");
int j;
printf("輸入刪除的位置：");
scanf("%d", &j);
deletelinkdblist(head, j);
print(head);
system("pause");
printf("\n");
}