第24题： 链表操作， （1）.单链表就地逆置

#include <iostream>
struct Node
{
    Node* next;
    int data;
    Node(int d = 0, Node* r = NULL):data(d),next(r) {}
};
Node* RecReverse(Node* head)
{
    if (head == NULL || head->next == NULL)
    {
        return head;
    }
    Node *newhead = RecReverse(head->next);
    head->next->next = head;
    head->next = NULL;
    return newhead;
}

Node* Reverse(Node* head)
{
    if (head == NULL || head->next == NULL)
    {
        return head;
    }
    Node* prev = head;
    Node* now = head->next;
    Node* tmp;
    while (now)
    {
        tmp = now;
        now = now->next;
        tmp->next = prev;
        prev = tmp;
    }
    head->next = NULL;
    return prev;
}

int main()
{
    Node* root = new Node(1);
    root->next = new Node(2);
    root->next->next = new Node(5);
    Node* newhead = Reverse(root);
    Node* tmp = newhead;
    for (; tmp; tmp = tmp->next)
    {
        printf("%d,",tmp->data);
    }
      return 0;
 }