循环链表
代码实现如下：
1 #include <cstdio> 2 #include <cstdlib> 3 4 typedef int itemType; 5 struct Node; 6 typedef struct Node *pNode; 7 typedef pNode list; 8 typedef pNode position; 9 10 struct Node { 11 itemType item; 12 position prev, next; 13 }; 14 15 list 16 MakeEmpty(list l) 17 { 18 l->item = 0; 19 l->prev = NULL; 20 l->next = l; 21 } 22 23 int 24 IsEmpty(list l) 25 { 26 /* 27 if (l->next == NULL) { 28 return 1; 29 } else { 30 return 0; 31 } 32 */ 33 return l->next == NULL; 34 } 35 36 int 37 IsLast(position p, list l) 38 { 39 return p->next == l; 40 } 41 42 position 43 Find(itemType item, list l) 44 { 45 position p; 46 47 p = l->next; 48 while (p != l && p->item != item) { 49 p = p->next; 50 } 51 52 return p; 53 } 54 /* 55 position 56 FindPrevious(itemType item, list l) 57 { 58 position p; 59 60 p = l; 61 while (p->next != NULL && p->next->item != item) { 62 p = p->next; 63 } 64 65 return p; 66 } 67 */ 68 void 69 Delete(itemType item, list l) 70 { 71 position p, tmp; 72 73 p = Find(item, l); 74 75 if (p != l) { 76 p->next->prev = p->prev; 77 p->prev->next = p->next; 78 free(p); 79 } 80 } 81 82 void 83 Insert(itemType item, list l, position p) 84 { 85 position tmp; 86 87 tmp = (position)malloc(sizeof(struct Node)); 88 if (tmp == NULL) { 89 printf("Out of space!\n"); 90 return; 91 } 92 93 tmp->item = item; 94 tmp->next = p->next; 95 tmp->prev = p; 96 p->next = tmp; 97 if (IsLast(tmp, l)) { 98 l->prev = tmp; 99 } 100 } 101 102 void 103 DeleteList(list l) 104 { 105 position p, tmp; 106 107 p = l->next; 108 while (p != NULL) { 109 tmp = p; 110 p = p->next; 111 free(tmp); 112 } 113 free(l); 114 } 115 116 position 117 Header(list l) 118 { 119 return l; 120 } 121 122 position 123 First(list l) 124 { 125 return l->next; 126 } 127 128 position 129 Advance( position p ) 130 { 131 return p->next; 132 } 133 134 itemType 135 Retrieve( position p ) 136 { 137 return p->item; 138 } 139 140 void 141 PrintList( list l) 142 { 143 position p; 144 p = First(l); 145 while (p != l) { 146 printf("%d\t", Retrieve(p)); 147 p = Advance(p); 148 } 149 printf("\n"); 150 } 151 152 int 153 main(int argc, char** argv) 154 { 155 list l; 156 // init 157 l = (list)malloc(sizeof(struct Node)); 158 MakeEmpty(l); 159 // insert some elememts 160 position p; 161 p = Header(l); 162 for (int i = 1; i < 11; i++) { 163 Insert(i, l, p); 164 p = Advance(p); 165 } 166 // retrieve 167 PrintList(l); 168 // find and delete 169 Delete(1, l); 170 Delete(10, l); 171 Delete(100, l); 172 PrintList(l); 173 174 printf("%d\n", l->prev->item); 175 176 system("pause"); 177 return 0; 178 }
