pta-数据结构与算法题目集（中文）-4-1-单链表逆转

函数接口定义：

List Reverse( List L );

typedef struct Node *PtrToNode;
struct Node {
ElementType Data; /* 存储结点数据 */
PtrToNode   Next; /* 指向下一个结点的指针 */
};
typedef PtrToNode List; /* 定义单链表类型 */

裁判测试程序样例：

#include <stdio.h>
#include <stdlib.h>

typedef int ElementType;
typedef struct Node *PtrToNode;
struct Node {
ElementType Data;
PtrToNode   Next;
};
typedef PtrToNode List;

List Read(); /* 细节在此不表 */
void Print( List L ); /* 细节在此不表 */

List Reverse( List L );

int main()
{
List L1, L2;
L1 = Read();
L2 = Reverse(L1);
Print(L1);
Print(L2);
return 0;
}

/* 你的代码将被嵌在这里 */

输入样例：

5
1 3 4 5 2

输出样例：

1
2 5 4 3 1

#include <stdio.h>
#include <stdlib.h>

typedef int ElementType;
typedef struct Node *PtrToNode;
struct Node {
ElementType Data;
PtrToNode   Next;
};
typedef PtrToNode List;

List Read(); /* 细节在此不表 */
void Print( List L ); /* 细节在此不表 */

List Reverse( List L );

int main()
{
List L1, L2;
L1 = Read();
L2 = Reverse(L1);
Print(L1);
Print(L2);
return 0;
}

List Read(){
int len = 0;
int num = 0;
PtrToNode list = NULL;
PtrToNode last = NULL;

scanf( "%d",&len );
if(  0 == len  ){
return NULL;
}

scanf( "%d",&num );
list = ( PtrToNode )malloc( sizeof( struct Node ) );
list->Data = num;
list->Next = NULL;
last = list;
len--;
while(  len > 0  ){
scanf( "%d",&num );
PtrToNode node = ( PtrToNode )malloc( sizeof( struct Node ) );
node->Data = num;
node->Next = NULL;
last->Next = node;
last = node;
len--;
}

return list;
}

void Print( List L ){
if( NULL == L  ){
return ;
}

PtrToNode last = L;

while(  NULL != last  ){
printf( "%d ",last->Data );
last = last->Next;
}
putchar( '\n' );
}

List Reverse( List L ){
if(  NULL == L  ){

return NULL;
}

PtrToNode listre = NULL;
PtrToNode t = L->Next;
if( NULL == t  ){
listre = L;
return listre;
}
L->Next = t->Next;
listre = t;
t->Next = L;

while(  NULL != L->Next  ){
t = L->Next;
L->Next = t->Next;
t->Next = listre;
listre = t;
}

return listre;
}