Data Structure Linked List: Reverse a Linked List in groups of given size

http://www.geeksforgeeks.org/reverse-a-list-in-groups-of-given-size/

#include <iostream>
#include <vector>
#include <algorithm>
#include <queue>
#include <stack>
#include <string>
#include <fstream>
#include <map>
#include <set>
using namespace std;

struct node {
    int data;
    node *next;
    node() : data(0), next(NULL) { }
    node(int d) : data(d), next(NULL) { }
};

void push(node* &head, int k) {
    node *new_node = new node(k);
    new_node->next = head;
    head = new_node;
}

node* reverselist(node *&head, int k) {
    node *cur = head;
    node *pre = NULL;
    node *next;
    int c = 0;
    while (cur && c < k) {
        next = cur->next;
        cur->next = pre;
        pre = cur;
        cur = next;
        c++;
    }
    if (next) head->next = reverselist(next, k);
    return pre;
}

void print(node *head) {
    while (head) {
        cout << head->data << " ";
        head = head->next;
    }
}

int main() {
    node *head = NULL;
    push(head, 8);
    push(head, 7);
    push(head, 6);
    push(head, 5);
    push(head, 4);
    push(head, 3);
    push(head, 2);
    push(head, 1);
    head = reverselist(head, 3);
    print(head);
    return 0;
}