6-2 带头结点的链式表操作集 （15 分）
本题要求实现带头结点的链式表操作集。
函数接口定义：
List MakeEmpty();
Position Find( List L, ElementType X );
bool Insert( List L, ElementType X, Position P );
bool 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：
List MakeEmpty()：创建并返回一个空的线性表；
Position Find( List L, ElementType X )：返回线性表中X的位置。若找不到则返回ERROR；
bool Insert( List L, ElementType X, Position P )：将X插入在位置P指向的结点之前，返回true。如果参数P指向非法位置，则打印“Wrong Position for Insertion”，返回false；
bool Delete( List L, Position P )：将位置P的元素删除并返回true。若参数P指向非法位置，则打印“Wrong Position for Deletion”并返回false。
裁判测试程序样例：
#include <stdio.h>
#include <stdlib.h>
#define ERROR NULL
typedef enum {false, true} bool;
typedef int ElementType;
typedef struct LNode *PtrToLNode;
struct LNode {
ElementType Data;
PtrToLNode Next;
};
typedef PtrToLNode Position;
typedef PtrToLNode List;
List MakeEmpty();
Position Find( List L, ElementType X );
bool Insert( List L, ElementType X, Position P );
bool Delete( List L, Position P );
int main()
{
List L;
ElementType X;
Position P;
int N;
bool flag;
L = MakeEmpty();
scanf("%d", &N);
while ( N-- ) {
scanf("%d", &X);
flag = Insert(L, X, L->Next);
if ( flag==false ) 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 {
flag = Delete(L, P);
printf("%d is found and deleted.\n", X);
if ( flag==false )
printf("Wrong Answer.\n");
}
}
flag = Insert(L, X, NULL);
if ( flag==false ) printf("Wrong Answer\n");
else
printf("%d is inserted as the last element.\n", X);
P = (Position)malloc(sizeof(struct LNode));
flag = Insert(L, X, P);
if ( flag==true ) printf("Wrong Answer\n");
flag = Delete(L, P);
if ( flag==true ) printf("Wrong Answer\n");
for ( P=L->Next; 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
代码：
List MakeEmpty()//创建返回新表
{
List L;
L=(List)malloc(sizeof(struct LNode));
L->Next=NULL;
return L;
}
Position Find( List L, ElementType X )//查找返回位置
{
while(L)
{
if(L->Data==X)
return L;
L=L->Next;
}
return ERROR;
}
bool Insert( List L, ElementType X, Position P )//插入
{
List t;//定义一个新节点t
t=(List)malloc(sizeof(struct LNode));
t->Data=X;
t->Next=NULL;
while(L)
{
if(L->Next==P)
{
t->Next=P;
L->Next=t;
return true;
}
L=L->Next;
}
printf("Wrong Position for Insertion\n");//位置非法！
return false;
}
bool Delete( List L, Position P )//删除
{
while(L)
{
if(L->Next==P)
{
L->Next=L->Next->Next;
return true;
}
L=L->Next;
}
printf("Wrong Position for Deletion\n");
return false;
}