数据结构及算法——带头结点的链式表操作集（C语言）

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：

[code]#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

【答案】：

[code]List MakeEmpty(){
    List A;
    A=(List)malloc(sizeof(struct LNode));
    A->Next=NULL;
    return A;
}
Position Find(List L,ElementType X){
    Position p;
    p=L;
    for(;p->Data!=X&&p;p=p->Next);
    if(p==NULL)return ERROR;
    else return p;
}

bool Insert(List L,ElementType X,Position P){
    Position pre,r;

    for(pre=L;pre&&pre->Next!=P;pre=pre->Next);
    if(pre==NULL){
        printf("Wrong Position for Insertion");
        return false;
    }
    else{
        r=(Position)malloc(sizeof(struct LNode));
        r->Data=X;
        r->Next=P;
        pre->Next=r;
        return true;
    }
}
bool Delete(List L,Position P){
    Position pre;
    for(pre=L;pre&&pre->Next!=P;pre=pre->Next);
    if(pre==NULL||P==NULL){
        printf ("Wrong Position for Deletion");
        return false;
    }
    else{
        pre->Next=P->Next;
        free(P);
        return true;
        }
    }