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吐槽下PTA,居然一个换行符跟我计较,恶心。
以下是正题:
本题要求实现链式表的操作集。
函数接口定义:
Position Find( List L, ElementType X );
List Insert( List L, ElementType X, Position P );
List 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:
Position Find( List L, ElementType X )
:返回线性表中首次出现X的位置。若找不到则返回ERROR;
List Insert( List L, ElementType X, Position P )
:将X插入在位置P指向的结点之前,返回链表的表头。如果参数P指向非法位置,则打印“Wrong Position for Insertion”,返回ERROR;
List Delete( List L, Position P )
:将位置P的元素删除并返回链表的表头。若参数P指向非法位置,则打印“Wrong Position for Deletion”并返回ERROR。
裁判测试程序样例:
#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
我的解答:
//返回线性表中首次出现X的位置。若找不到则返回ERROR;
Position Find( List L, ElementType X )
{
List p=L;
while(p!=NULL&&(p->Data!=X))
{
p=p->Next;
}
//return p;
if ( p )
return p;
else
return ERROR;
}
/*
将X插入在位置P指向的结点之前,
返回链表的表头。
如果参数P指向非法位置,
则打印“Wrong Position for Insertion”,返回ERROR;
*/
List Insert( List L, ElementType X, Position P )
{
List tmp;
List pre;
//1先考虑特殊情况:P插入在表头,没有前面的节点,直接申请填装
if(P==L)
{
tmp = (Position)malloc(sizeof(struct LNode));
tmp->Data = X;
tmp->Next = P;
return tmp;
}
//2查找P-1个节点,如果不存在就无法插入,存在就可以插入
/* 查找P的前一个结点 */
for ( pre=L; pre&&pre->Next!=P; pre=pre->Next ) ;
if ( pre==NULL )
{ /* P所指的结点不在L中 */
printf("Wrong Position for Insertion\n");
return ERROR;
}
//3存在P-1个节点,申请、填装节点
//4将新节点装在P-1个节点后面
else /* 找到了P的前一个结点pre */
{
/* 在P前插入新结点 */
tmp = (Position)malloc(sizeof(struct LNode));
tmp->Data = X;
tmp->Next = P;
pre->Next = tmp;
return L;
}
}
/*
将位置P的元素删除并返回链表的表头。
若参数P指向非法位置,
则打印“Wrong Position for Deletion”并返回ERROR。
*/
List Delete( List L, Position P )
{
List removeP,temP;
/********如果删除的是头的话*********/
if(P==L)
{
removeP=L;
if(L!=NULL)
{
L=L->Next;
}
//释放空间
free(removeP);
return L;
}
/********删除第P个节点*********/
//1先找到P-1个节点,用temP指向
for ( temP=L; temP&&temP->Next!=P; temP=temP->Next ) ;
if(temP==NULL)
{
printf("Wrong Position for Deletion\n");
return ERROR;
}
if(temP->Next==NULL)
{
printf("Wrong Position for Deletion\n");
return ERROR;
}
//2将要删除的P给removeP
removeP=temP->Next;
//3将temP的next赋值"为"remoP的next
temP->Next=removeP->Next;
//4释放removeP的空间
free(removeP);
//5返回L
return L;
}