6-10 帶頭結點的鏈式表操作集 （20 分）
本題要求實現帶頭結點的鏈式表操作集。
函數接口定義：
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;
各個操作函數的定義爲：
List MakeEmpty()：創建並返回一個空的線性表；
Position Find( List L, ElementType X )：返回線性表中X的位置。若找不到則返回ERROR；
bool Insert( List L, ElementType X, Position P )：將X插入在位置P指向的結點之前，返回true。如果參數P指向非法位置，則打印“Wrong Position for Insertion”，返回false；
bool Delete( List L, Position P )：將位置P的元素刪除並返回true。若參數P指向非法位置，則打印“Wrong Position for Deletion”並返回false。
裁判測試程序樣例：
#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;
}
/* 你的代碼將被嵌在這裏 */
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
List MakeEmpty() {
List p;
p=(Position)malloc(sizeof(struct LNode));
p->Data =0;
p->Next =NULL;
return p;
}
Position Find( List L, ElementType X ) {
List p=L;
while(p->Next) {
if(p->Next->Data==X) {
return p->Next;
}
p=p->Next ;
}
return ERROR;
}
bool Insert( List L, ElementType X, Position P ) {
Position tmp,pre;
pre=L;
while(pre->Next!=NULL && pre->Next !=P)
pre=pre->Next ;
if(pre->Next==P) {
tmp=(Position)malloc(sizeof(struct LNode));
tmp->Data=X;
tmp->Next=pre->Next;
pre->Next =tmp;
return true;
} else {
printf("Wrong Position for Insertion\n");
return false;
}
}
bool Delete( List L, Position P ) {
Position tmp,pre;
pre=L;
while(pre->Next!=NULL &&pre->Next !=P)
pre=pre->Next ;
if(pre->Next==P) {
tmp=pre->Next ;
pre->Next =tmp->Next;
free(tmp);
return true;
}
else
{
printf("Wrong Position for Deletion\n");
return false;}
}