1 /*
2 简介：双向链表，可在头尾实现插入和删除
3 注意：这个双向链表不形成环
4 作者：njit-sam(许言)
5 */
6
7 #include <stdio.h>
8 #include <stdlib.h>
9 #include <string.h>
10
11 typedef struct double_linked_list {
12 int index;
13 struct double_linked_list* pre;
14 struct double_linked_list* next;
15 void (*print)(void* p);
16 } s_double_linked_list, *ps_double_linked_list;
17
18 ps_double_linked_list phead = NULL;
19 ps_double_linked_list ptail = NULL;
20
21 void print(void* p) { printf("index=%d\n", *(int*)p); }
22
23 void double_linked_list_init() {
24 printf("init\n");
25 phead = ptail = NULL;
26 }
27
28 void double_linked_list_insert_head() {
29 if (phead == NULL) {
30 ps_double_linked_list pdll = malloc(sizeof(s_double_linked_list));
31 memset(pdll, '\0', sizeof(s_double_linked_list));
32 pdll->index = 1;
33 pdll->pre = pdll;
34 pdll->next = NULL;
35 pdll->print = print;
36 phead = pdll;
37 ptail = pdll;
38 } else {
39 ps_double_linked_list pdll = malloc(sizeof(s_double_linked_list));
40 memset(pdll, '\0', sizeof(s_double_linked_list));
41 pdll->index = 1;
42 pdll->print = print;
43 pdll->pre = pdll;
44 pdll->next = phead;
45 phead->pre = pdll;
46 phead = pdll;
47 /*重新整理index,使之从1开始有序*/
48 int index = 1;
49 ps_double_linked_list ptemp = phead->next;
50 while (ptemp != NULL) {
51 ptemp->index = ++index;
52 ptail = ptemp;
53 ptemp = ptemp->next;
54 }
55 }
56 }
57
58 void double_linked_list_insert_tail() {
59 if (ptail == NULL) {
60 ps_double_linked_list pdll = malloc(sizeof(s_double_linked_list));
61 memset(pdll, '\0', sizeof(s_double_linked_list));
62 pdll->index = 1;
63 pdll->pre = pdll;
64 pdll->next = NULL;
65 pdll->print = print;
66 phead = pdll;
67 ptail = pdll;
68 } else {
69 ps_double_linked_list pdll = malloc(sizeof(s_double_linked_list));
70 memset(pdll, '\0', sizeof(s_double_linked_list));
71 pdll->index = ptail->index + 1;
72 pdll->print = print;
73 pdll->pre = ptail;
74 pdll->next = NULL;
75 ptail->next = pdll;
76 ptail = pdll;
77 }
78 }
79
80 void double_linked_list_remove_head() {
81 if (phead == NULL)
82 return;
83 if (phead->next == NULL) {
84 free(phead);
85 phead = ptail = NULL;
86 } else {
87 ps_double_linked_list ptemp;
88 ptemp = phead->next;
89 ptemp->pre = ptemp;
90 free(phead);
91 phead = ptemp;
92 /*重新整理index,使之从1开始有序*/
93 int index = 0;
94 ptemp = phead;
95 while (ptemp != NULL) {
96 ptemp->index = ++index;
97 ptail = ptemp;
98 ptemp = ptemp->next;
99 }
100 }
101 }
102
103 void double_linked_list_remove_tail() {
104 if (ptail == NULL)
105 return;
106 if (ptail->pre == ptail) {
107 free(ptail);
108 phead = ptail = NULL;
109 } else {
110 ps_double_linked_list ptemp;
111 ptemp = ptail->pre;
112 ptemp->next = NULL;
113 free(ptail);
114 ptail = ptemp;
115 }
116 }
117
118 void double_linked_list_print() {
119 ps_double_linked_list ptemp = phead;
120 while (ptemp != NULL) {
121 ptemp->print(&ptemp->index);
122 ptemp = ptemp->next;
123 }
124 }
125
126 int main(void) {
127 printf("Hello World\n");
128 double_linked_list_init();
129 double_linked_list_insert_head();
130 double_linked_list_insert_head();
131 double_linked_list_insert_head();
132 double_linked_list_insert_head();
133 double_linked_list_insert_head();
134 double_linked_list_insert_tail();
135 double_linked_list_insert_tail();
136 double_linked_list_insert_tail();
137 double_linked_list_insert_tail();
138 double_linked_list_print();
139 double_linked_list_remove_head();
140 double_linked_list_remove_head();
141 double_linked_list_print();
142 double_linked_list_remove_tail();
143 double_linked_list_remove_tail();
144 double_linked_list_print();
145 return 0;
146 }
