反转链表

未测试边界条件

#include <iostream>

using namespace std;

struct node{
  int data;
  node *next;

  node(int m_data, node *m_next = NULL){
    data = m_data;
    next = m_next;
  }
};

node *reverse_list_circularly(node *head){
  node *pNode = head;
  node *next = NULL;
  node *prev = NULL;
  node *reverse_head = NULL;

  while(pNode != NULL){
    next = pNode->next;

    if (next == NULL)
      reverse_head = pNode;

    pNode->next = prev;

    prev = pNode;
    pNode = next;
  }

  return reverse_head;
}

node *revere_list_recursively(node *prev, node *pNode){
  node *next = pNode->next;

  if (next == NULL){
    pNode->next = prev;
    return pNode;
  }

  pNode->next = prev;

  prev = pNode;
  pNode = next;

  revere_list_recursively(prev, pNode);
}

int main(){
  node *head = new node(1);
  node *pNode = head;

  pNode->next = new node(2);
  pNode = pNode->next;
  
  pNode->next = new node(3);
  pNode = pNode->next;

  pNode->next = new node(4);
  pNode = pNode->next;

  for (pNode = head; pNode != NULL; pNode = pNode->next){
    cout << pNode->data <<endl;
  }
  cout << endl;

  //反转链表(循环)
  head = reverse_list_circularly(head);

  for (pNode = head; pNode != NULL; pNode = pNode->next){
    cout << pNode->data <<endl;
  }
  cout << endl;

  //反转链表（递归）
  head = revere_list_recursively(NULL, head);
  for (pNode = head; pNode != NULL; pNode = pNode->next){
    cout << pNode->data <<endl;
  }
  cout << endl;


  int ttt = 0;

  return 0;
}