reverse a linked list with array as member

reverseLinkList.cpp

#include <iostream>
#include <vector>
using namespace std;

struct ListNode {
  vector<int> vec;
  ListNode *next;

  ListNode() : next(NULL) {};
  ListNode(int start, int end) : next(NULL) {
    for (int i = start; i <= end; i++) {
      vec.push_back(i);
    }
  }
};

void printList(ListNode *head) {
  ListNode *node = head;

  while (node != NULL) {
    cout << "(";
    for (int i = 0; i < node->vec.size(); i++) {
      cout << node->vec[i] << ", ";
    }
    cout << ") ==> ";
    node = node->next;
  }
  cout << endl;
}

// build a sample list
ListNode *buildList() {
  ListNode *node1 = new ListNode(1, 3);
  ListNode *node2 = new ListNode(4, 8);
  node1->next = node2;
  ListNode *node3 = new ListNode(9, -1);
  node2->next = node3;
  ListNode *node4 = new ListNode(9, 9);
  node3->next = node4;
  ListNode *node5 = new ListNode(10, 12);
  node4->next = node5;
  return node1;
}

ListNode *reverseList(ListNode *head) {
  ListNode *prev = NULL;
  ListNode *temp = head;
  while (temp != NULL) {
    ListNode *next = temp->next;
    temp->next = prev;
    prev = temp;
    temp = next;
  }
  return prev;
}

int main() {
  ListNode *head = buildList();
  printList(head);
  ListNode *newHead = reverseList(head);
  printList(newHead);
  return 0;
}