单链表（二）

  1 /*
  2  * 第二版链表实现 
  3  * 原先的实现，是以哑节点的方式来做链表的头部。
  4  * 现在我们使用一个指针来做链表的头部，节约一个struct Node的空间 
  5  */
  6 
  7 #include <cstdio>
  8 #include <cstdlib>
  9 
 10 typedef int itemType;
 11 struct Node;
 12 typedef struct Node *pNode;
 13 typedef pNode list;
 14 typedef pNode position;
 15 
 16 struct Node {
 17     itemType item;
 18     position next;
 19 };
 20 
 21 int
 22 IsEmpty(list l)
 23 {
 24     return l == NULL;
 25 }
 26 
 27 int
 28 IsLast(position p, list l)
 29 {
 30     return p->next == NULL;
 31 }
 32 
 33 position
 34 Find(itemType item, list l)
 35 {
 36     while (l != NULL && l->item != item) {
 37         l = l->next;
 38     }
 39     
 40     return NULL;
 41 }
 42 
 43 list
 44 Delete(itemType item, list l)
 45 {
 46     position p, prev;
 47     prev = NULL;
 48     
 49     for (p = l; p != NULL; p = p->next) {
 50         if (p->item != item) {
 51             prev = p;
 52         } else {
 53             if (prev == NULL) {
 54                 l = l->next;
 55             } else {
 56                 prev->next = p->next;
 57             }
 58             free(p);
 59             return l;
 60         }
 61     }
 62     
 63     printf("Item: %d is not found!\n", item);
 64     return l;         
 65 }
 66 
 67 list
 68 InsertFront(itemType x, list l) {
 69     position newNode;
 70     newNode = (position)malloc(sizeof(struct Node));
 71     if (newNode == NULL) {
 72         printf("Out of space!\n");
 73         return NULL;
 74     }
 75     
 76     newNode->item = x;
 77     newNode->next = l;
 78     return newNode;
 79 }
 80 
 81 void
 82 DeleteList(list l)
 83 {
 84     position p, tmp;
 85     
 86     p = l;
 87     while (p != NULL) {
 88         tmp = p;
 89         p = p->next;
 90         free(tmp);
 91     }   
 92 }
 93 
 94 position
 95 Header(list l)
 96 {
 97     return l;
 98 }
 99 
100 position
101 Advance( position p )
102 {
103     return p->next;
104 }
105 
106 itemType
107 Retrieve( position p )
108 {
109     return p->item;
110 }
111 
112 void
113 PrintList( list l)
114 {
115     position p;
116     p = Header(l);
117     while (p != NULL) {
118         printf("%d\t", Retrieve(p));
119         p = Advance(p);
120     }
121     printf("\n");
122 }
123 
124 int
125 main(int argc, char** argv)
126 {
127     list l;
128     l = NULL;
129     // insert some elememts
130     for (int i = 0; i < 10; i++) {
131         l = InsertFront(i, l);
132     }
133     // retrieve
134     PrintList(l);
135     // find and delete
136     l = Delete(0, l);
137     l = Delete(9, l);
138     l = Delete(100, l);
139     PrintList(l);
140     
141     system("pause");
142     return 0;
143 }