PTA 带头结点的链式表操作集

6-2 带头结点的链式表操作集 (20 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

 1 List MakeEmpty(){
 2     List l=(List)malloc(sizeof(struct LNode));
 3     l->Data=0;
 4     l->Next=NULL;
 5     return l;
 6 }
 7
 8 Position Find( List L, ElementType X ){
 9     Position p=(Position)malloc(sizeof(Position));
10     while(L){
11         if(L->Data==X){
12             p=L;
13             return p;
14         }
15         L=L->Next;
16     }
17     return ERROR;
18 }//返回线性表中X的位置。若找不到则返回ERROR；
19
20 bool Insert( List L, ElementType X, Position P ){
21
22     Position n=(Position)malloc(sizeof(struct LNode));
23     n->Data=X;
24
25     while(L){
26         if(L->Next==P){
27             n->Next=P;
28             L->Next=n;
29             return true;
30         }
31         L=L->Next;
32     }
33 printf("Wrong Position for Insertion\n");
34         return false;
35 }//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；
36
37 bool Delete( List L, Position P ){
38
39     while(L){
40         if(L->Next==P){
41             L->Next=P->Next;
42             return true;
43         }
44         L=L->Next;
45     }
46     printf("Wrong Position for Deletion\n");
47         return false;
48 }//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。