链表逆序

list.h

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

void printList(List list);
List reverseList(List list);

list.cpp

#include <iostream>
using namespace std;
#include "list.h"

void main()
{
	ListNode* head;
	head = (ListNode*)malloc(sizeof(ListNode));
	head->next = NULL;
	head->data = -1;

	ListNode *p,*q;
	p = head;
	for (int i=0;i<10;++i)
	{
		q = (ListNode *)malloc(sizeof(ListNode));
		q->data = i;
		q->next = NULL;
		p->next = q;
		p = q;
	}

	printList(head);
	head = reverseList(head);
	printList(head);
}

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

List reverseList(List list)
{
	if (list->next==NULL||list->next->next==NULL)
		return list;

	ListNode *p = list->next;
	ListNode *q = list->next->next;
	ListNode *t = NULL;
	while(q!=NULL)
	{
		t = q->next;
		q->next = p;
		p = q;
		q = t;
	}

	//此时p指向原来的最后一个节点
	list->next->next = NULL;//list还是头节点，list->next是原来的第一个节点（即倒转后的尾节点）
	list->next = p;
	return list;
}