算法导论10.2-8C语言

  只用一个指针实现双链表.这道题,我按照我的思路写出来了.之前搜索了下,没有搜索到关于这道题的答案,于是一改以往作风,直接用题号作了标题,希望能被搜索到,呵呵.

  每个结点,只存储前后指针值的异或值.这样的话,只要知道前后任何一个结点的地址,就可以获得相反方向结点的地址,我用了一个全局变量来跟踪上一个结点的地址.这样,在执行完 Find_L () 之后,便可以实现向前或者向后的遍历,这样一来,是可以实现双向链表应有的功能的.

  这个的想法真的很好,以至于我不想错过他!确实,很受启发.如果有举一反三能力的话,依靠这个确实可以解决很多问题.XOR,很神奇啊.

  补充下啊...今天坐车我坐在了一个喜欢的女女的旁边.当时车上就一个空座.而且,如果我不是因为在车下面把烟抽完才上车的话,也不可能坐在她旁边,我一定会选择一个老爷们或者老太太的旁边坐下.呵呵.现在想想,呵呵...笑笑算了...为了理想,没办法.只能如此.

  好吧,贴出代码.

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/* 10.2-8-2011-05-09-18.35.c -- 第十章第二节第八题 */ #include <stdio.h> #include <stdlib.h> /* 明显常量定义 */ #define FALSE (0) #define TRUE (1) /* 数据类型定义 */ typedef int BOOL ; typedef int Item ; typedef struct node { Item item ; unsigned int pointerValue : sizeof (struct node *) * 8 ; } Node ; typedef Node * LinkedList ; /* 全局变量声明 */ static Node * LastNode ; /* 接口函数声明 */ void Initialize_L (LinkedList * const pl) ; BOOL IsEmpty_L (const LinkedList * const pl) ; BOOL Insert_L (LinkedList * const pl, const Item item) ; Node * Find_L (const LinkedList * const pl, const Item item) ; void Traversal_L (const LinkedList * pl, void (* pfun) (const Node * const pn)) ; void Delete_L (LinkedList * const pl, Node * const target) ; void Release_L (LinkedList * const pl) ; /* 接口函数定义 */ void Initialize_L (LinkedList * const pl) { *pl = NULL ; } BOOL IsEmpty_L (const LinkedList * const pl) { if (NULL == *pl) return TRUE ; else return FALSE ; } BOOL Insert_L (LinkedList * const pl, const Item item) { Node * newNode ; newNode = (Node *) malloc (sizeof (Node)) ; if (NULL == newNode) return FALSE ; newNode -> item = item ; if (IsEmpty_L (pl)) { newNode -> pointerValue = (unsigned int) NULL ; *pl = newNode ; } else { newNode -> pointerValue = (unsigned int) NULL ^ (unsigned int) *pl ; (*pl) -> pointerValue = (unsigned int) newNode ^ ((unsigned int) NULL ^ (*pl) -> pointerValue) ; *pl = newNode ; } return TRUE ; } Node * Find_L (const LinkedList * const pl, const Item item) { Node * scan, * record, * temp ; scan = *pl ; record = LastNode ; LastNode = NULL ; while (scan != NULL) { if (item == scan -> item) return scan ; else { temp = scan ; scan = (Node *) ((unsigned int) LastNode ^ scan -> pointerValue) ; LastNode = temp ; } } LastNode = record ; return NULL ; } void Traversal_L (const LinkedList * pl, void (* pfun) (const Node * const pn)) { Node * scan, * lastNode, * temp ; scan = *pl ; lastNode = NULL ; while (scan != NULL) { (* pfun) (scan) ; temp = scan ; scan = (Node *) ((unsigned int) lastNode ^ scan -> pointerValue) ; lastNode = temp ; } } /* target point to some node in the linked list. */ void Delete_L (LinkedList * const pl, Node * const target) { Node * nextNode ; /* If target is head node. */ if (*pl == target) { /* If only have one node in the linked list. */ if ((unsigned int) NULL == (*pl) -> pointerValue) { free (*pl) ; *pl = NULL ; } else { nextNode = (Node *) ((unsigned int) NULL ^ (*pl) -> pointerValue) ; nextNode -> pointerValue = (unsigned int) NULL ^ ((unsigned int) *pl ^ nextNode -> pointerValue) ; free (*pl) ; *pl = nextNode ; } } else { nextNode = (Node *) ((unsigned int) LastNode ^ target -> pointerValue) ; LastNode -> pointerValue = (LastNode -> pointerValue ^ (unsigned int) target) ^ (unsigned int) nextNode ; if (nextNode != NULL) nextNode -> pointerValue = (unsigned int) LastNode ^ ((unsigned int) target ^ nextNode -> pointerValue) ; free (target) ; } } void Release_L (LinkedList * const pl) { Node * scan, * temp ; unsigned int lastNodePointerValue = 0 ; scan = *pl ; while (scan != NULL) { temp = scan ; scan = (Node *) (lastNodePointerValue ^ scan -> pointerValue) ; lastNodePointerValue = (unsigned int) temp ; free (temp) ; } } /* 测试例程 */ int main (void) ; void printNode (const Node * const pn) ; int main (void) { LinkedList list ; Item item ; Initialize_L (&list) ; item = 1 ; Insert_L (&list, item) ; item = 2 ; Insert_L (&list, item) ; item = 3 ; Insert_L (&list, item) ; item = 4 ; Insert_L (&list, item) ; item = 5 ; Insert_L (&list, item) ; Traversal_L (&list, printNode) ; putchar ('/n') ; Delete_L (&list, Find_L (&list, 1)) ; Delete_L (&list, Find_L (&list, 5)) ; Delete_L (&list, Find_L (&list, 3)) ; Delete_L (&list, Find_L (&list, 2)) ; Delete_L (&list, Find_L (&list, 4)) ; item = 1 ; Insert_L (&list, item) ; item = 2 ; Insert_L (&list, item) ; item = 3 ; Insert_L (&list, item) ; item = 4 ; Insert_L (&list, item) ; item = 5 ; Insert_L (&list, item) ; Traversal_L (&list, printNode) ; Release_L (&list) ; return 0 ; } void printNode (const Node * const pn) { printf ("%d/n", pn -> item) ; }