4-6 带头结点的链式表操作集

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

#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;
}
List MakeEmpty(){
List l=(List) malloc((sizeof(struct LNode)));
l->Next=NULL;
return l;
}
Position Find( List L, ElementType X ){
Position temp;
while(L->Next!=NULL){
temp=L->Next;       //temp保存第一个节点
if(temp->Data==X)
return temp;
L=L->Next;
}
return ERROR;
}
bool Insert( List L, ElementType X, Position P ){
List apply = NULL;  //待插入的新节点
while(L->Next != P && L->Next != NULL)//若没找到P并且没到链尾则往下移动
L = L->Next;
if(L->Next == NULL&&P!=NULL){//如果已经到了链尾,说明P肯定不在链表里，而此时P又不为NULL，则一定是P出现了错误
printf("Wrong Position for Insertion\n");
return false;
}
else    //有三种情况：第一种L->Next!=NULL，P！=NULL是普通情况
{       //第二种L->Next!=NULL，P==NULL 这种情况不存在，
//因为若P==NULL，则退出while循环后L->Next或者走到L->Next=NULL或者L->Next=P仍为NULL，所以此种情况不存在。
//第三种L->Next==NULL，P==NULL 则插在链表末尾
apply = (List) malloc((sizeof(struct LNode)));
apply->Data = X;
L->Next = apply;
apply->Next = P;
return true;
}
}
bool Delete( List L, Position P ){
if(L->Next== NULL||P==NULL){    //如果只有头结点或者删除的位置是NULL，则不能删除
printf("Wrong Position for Deletion\n");
return false;
}
while(L->Next != P && L->Next != NULL)
L = L ->Next;
if(L->Next == NULL){    //P一定在链表上，如果始终没有找到P，则删除错误
printf("Wrong Position for Deletion\n");
return false;
}
else{   //否则删除P
L->Next = P->Next;
free(P);
return true;
}
}

题目链接：

https://pta.patest.cn/pta/test/15/exam/3/question/729