用递归和非递归的方法 逆置单链表

#include <iostream>
using namespace std;

struct Node
{
	int data;
	Node* next;
}*head;

// 非递归写法
Node* InverseLinkedList(Node* head)
{
	if(head == NULL)
		return NULL;
	Node* newHead = NULL;
	while(head != NULL)
	{
		Node* nextNode = head->next;
		head->next = newHead;
		newHead = head;
		head = nextNode;
	}
	return newHead;
}

// 递归写法
Node* InverseLinkedListRecur(Node* head)
{
	if(head == NULL)
		return NULL;
	if(head->next == NULL)
		return head;
	Node* newHead = InverseLinkedListRecur(head->next);
	Node *tmp = newHead;
	while(tmp->next != NULL)
	{
		tmp = tmp->next;
	}
	tmp->next = head;
	head->next = NULL;
	return newHead;
}

int main()
{
	// 构建链表 9->8->7->6->5->4->3->2->1->0->NULL
	for(int i = 0; i < 10; i++)
	{
		Node* node = new Node();
		node->data = i;
		node->next = head;
		head = node;
	}
	head = InverseLinkedList(head);
	Node *tmp = head;
	while(head != NULL)
	{
		cout << head->data << " ";
		head = head->next;
	}
	cout << endl;
	head = InverseLinkedListRecur(tmp);
	tmp = head;
	while(head != NULL)
	{
		cout << head->data << " ";
		head = head->next;
	}
	cout << endl;
	while(tmp != NULL)
	{
		Node* next = tmp->next;
		delete tmp;
		tmp = next;
	}
}