6-6 带头结点的链式表操作集 (20分)

List MakeEmpty(); 
Position Find( List L, ElementType X );
bool Insert( List L, ElementType X, Position P );
bool Delete( List L, Position P );

typedef struct LNode *PtrToLNode;
struct LNode {
    ElementType Data;
    PtrToLNode Next;
};
typedef PtrToLNode Position;
typedef PtrToLNode List;

#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 */

6
12 2 4 87 10 2
4
2 12 87 5

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 

List MakeEmpty()//创建并返回一个空的线性表
{
    List head=(List )malloc(sizeof(struct LNode));
    head->Next=NULL;
    return head;
}
Position Find(List L,ElementType X)
{
    List p=L->Next;
    while(p!=NULL)
    {
        if(p->Data==X)
            return p;
        else
            p=p->Next;
    }
    return ERROR;
}
bool Insert( List L, ElementType X, Position P )
{
    List p=L;
    while(p!=NULL)
    {
        if(p->Next==P)
        {
            List q=(List)malloc(sizeof(struct LNode));
            q->Data=X;
            q->Next=p->Next;
            p->Next=q;
            return true;
        }
        p=p->Next;
    }
    printf("Wrong Position for Insertion\n");
    return false;
}
bool Delete( List L, Position P )
{
    List p=L;
    while(p)
    {
        if(p->Next==P)
        {
            p->Next=p->Next->Next;
            free(P);
            return true;
        }
        p=p->Next;
    }
    printf("Wrong Position for Deletion\n");
    return false;
}