单链表的就地逆置 （单链表带头结点）（某公司校园招聘面试试题）

#include<iostream>
using namespace std;

typedef struct node
{
int data;
struct node *next;
}Node, *List;

List createList()
{
Node *head, *p1, *p2;
p1 = p2 = head = new Node;

int num;
cin >> num;
while(-1 != num)
{
p1 = new Node;
p1->data = num;
p2->next = p1;
p2 = p1;
cin >> num;
}
p2->next = NULL;

return head;
}

void printList(List p)
{
while(NULL != p->next)
{
cout << p->next->data << " ";
p = p->next;
}
cout << endl;
}

void releaseList(List p)
{
if(NULL == p->next)
delete p;
else
{
releaseList(p->next);
delete p;
}
}

List reverseList(List p)
{
//让p1和p2都指向第一个结点
Node *p1 = p->next;
Node *p2 = p1;

p->next = NULL;//分离p与p1

while(NULL != p1)
{
p2 = p1;
p1 = p1->next; //在"摘下" p2时，千万记得先进行p1 = p1->next;

//倒插法重建链表
p2->next = p->next;
p->next = p2;
}

return p;
}

int main()
{
List head = createList();
printList(head);

reverseList(head);
printList(head);

releaseList(head);

return 0;
}