本題要求實現鏈式表的操作集。

函式介面定義：

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

其中List結構定義如下：

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

各個操作函式的定義為：

Position Find( List L, ElementType X )：返回線性表中首次出現X的位置。若找不到則返回ERROR；

List Insert( List L, ElementType X, Position P )：將X插入在位置P指向的結點之前，返回連結串列的表頭。如果引數P指向非法位置，則列印“Wrong Position for Insertion”，返回ERROR；

List Delete( List L, Position P )：將位置P的元素刪除並返回連結串列的表頭。若引數P指向非法位置，則列印“Wrong Position for Deletion”並返回ERROR。

裁判測試程式樣例：

#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");
    else
        printf("%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;
}

/* 你的程式碼將被嵌在這裡 */
 

輸入樣例：

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

輸出樣例：

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

程式程式碼：

Position Find( List L, ElementType X )
{
	List p=L;
	while(p)
	{
		if(p->Data==X)
			return p;
		p=p->Next;
	}
	return ERROR;
}

List Insert(List L,ElementType X,Position P)//注意題目要求返回表頭 
{
	List p=L;
	if(L==P)//當L==P時（包括L==P==NULL）在表頭前插入節點直接返回該節點 
	{
		List s=(struct LNode*)malloc(sizeof(struct LNode));
		s->Data=X;
		s->Next=L;
		L=s;
		return L;
	}
	if(L==NULL)
	{
		printf("Wrong Position for Insertion\n");
		return ERROR;
	}
	while(L->Next!=NULL&&L->Next!=P)
		L=L->Next;
	if(L->Next==NULL&&P!=NULL)
	{
		printf("Wrong Position for Insertion\n");
		return ERROR;
	}
	List s=(struct LNode*)malloc(sizeof(struct LNode));
	s->Data=X;
	L->Next=s;
	s->Next=P;
	return p;
}

List Delete( List L, Position P )
{
	List p=L;
	if(P==NULL||L==NULL)
	{
		printf("Wrong Position for Deletion\n");
		return ERROR; 
	}
	if(L==P)
	{
		List l=L;
		l=l->Next;
		free(L);
		return l;
	}
	while(L->Next!=NULL&&L->Next!=P)
	{
		L=L->Next;
	}
	if(L->Next==NULL&&P!=NULL)
	{
		printf("Wrong Position for Deletion\n");
		return ERROR; 
	}
	L->Next=P->Next;
	free(P);
	return p;
}