本题要求实现链式表的操作集。
函数接口定义：
Position Find( List L, ElementType X );
List Insert( List L, ElementType X, Position P );
List Delete( List L, Position P );
其中List结构定义如下：
typedef struct LNode *PtrToLNode;
struct LNode {ElementType Data;PtrToLNode Next;
};
typedef PtrToLNode Position;
typedef PtrToLNode List;
各个操作函数的定义为：
Position Find( List L, ElementType X )：返回线性表中首次出现X的位置。若找不到则返回ERROR；
List Insert( List L, ElementType X, Position P )：将X插入在位置P指向的结点之前，返回链表的表头。如果参数P指向非法位置，则打印“Wrong Position for Insertion”，返回ERROR；
List Delete( List L, Position P )：将位置P的元素删除并返回链表的表头。若参数P指向非法位置，则打印“Wrong Position for Deletion”并返回ERROR。
裁判测试程序样例：
#include <stdio.h>
#include <stdlib.h>#define ERROR NULL
typedef int ElementType;
typedef struct LNode *PtrToLNode;
struct LNode {ElementType Data;PtrToLNode Next;
};
typedef PtrToLNode Position;
typedef PtrToLNode List;Position Find( List L, ElementType X );
List Insert( List L, ElementType X, Position P );
List Delete( List L, Position P );int main()
{List L;ElementType X;Position P, tmp;int N;L = NULL;scanf("%d", &N);while ( N-- ) {scanf("%d", &X);L = Insert(L, X, L);if ( L==ERROR ) printf("Wrong Answer\n");}scanf("%d", &N);while ( N-- ) {scanf("%d", &X);P = Find(L, X);if ( P == ERROR )printf("Finding Error: %d is not in.\n", X);else {L = Delete(L, P);printf("%d is found and deleted.\n", X);if ( L==ERROR )printf("Wrong Answer or Empty List.\n");}}L = Insert(L, X, NULL);if ( L==ERROR ) printf("Wrong Answer\n");elseprintf("%d is inserted as the last element.\n", X);P = (Position)malloc(sizeof(struct LNode));tmp = Insert(L, X, P);if ( tmp!=ERROR ) printf("Wrong Answer\n");tmp = Delete(L, P);if ( tmp!=ERROR ) printf("Wrong Answer\n");for ( P=L; P; P = P->Next ) printf("%d ", P->Data);return 0;
}/* 你的代码将被嵌在这里 */
输入样例：
6
12 2 4 87 10 2
4
2 12 87 5
输出样例：
2 is found and deleted.
12 is found and deleted.
87 is found and deleted.
Finding Error: 5 is not in.
5 is inserted as the last element.
Wrong Position for Insertion
Wrong Position for Deletion
10 4 2 5
Position Find(List L, ElementType X)
{
while (L)
{
if (L->Data == X)
return L;
if (L->Data != X)
L = L->Next;
}
return ERROR;
}在顺序表中是一次性申请好所有的空间，在插入的时候无需重新申请空间，而在链式表中每插入一次数据都要申请一次空间
//注意：
List Insert(List L, ElementType X, Position P)
{
List temp = (List)malloc(sizeof(struct LNode));//注意申请空间的格式写法
temp->Next = NULL;
temp->Data = X;
List head = L;//无论L链表如何改变，最终返回的都是链表的表头，所以使用head记录链表的表头
if (P == L)//如果是在头结点插入的话要另外处理
{
temp->Next = L;
return temp;
}
while (L->Next)
{
if (P == L->Next)
{
temp->Next = L->Next;//注意插入的顺序
L->Next = temp;
return head;
}
L = L->Next;
}
if (P == NULL)//指向链表中的最后一个
{
L->Next = temp;
return head;
}
else
{
printf("Wrong Position for Insertion\n");
return ERROR;
}
}
List Delete(List L, Position P)
{
List temp,pre,head;
if (P == L)//删除节点在开头的情况
{
temp = L;
L = L->Next;
free(temp);
return L;
}
head = L;
if (L->Next)
pre = L->Next;
while (L->Next)
{
if (L->Next == P&&L->Next->Next != NULL)
{
temp = L->Next;
pre = L->Next->Next;
L->Next = pre;
free(temp);
return head;
}
if (L->Next == P&&L->Next->Next == NULL)//特别讨论一下删除最后一个节点的情况
{
temp = L->Next;
L->Next = NULL;
free(temp);
return head;
}
pre = pre->Next;
L = L->Next;
}
printf("Wrong Position for Deletion\n");
return ERROR;
}