Odd Even Linked List

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */

struct Linked_List {
  ListNode *head = NULL;
  ListNode *tail = NULL;
  int num_elements = 0;
  void push(int value) {
    ListNode *new_node = new ListNode;
    new_node->val = value;
    new_node->next = NULL;
    if (head == NULL) {
      head = new_node;
      tail = head;
    } else {
      tail->next = new_node;
      tail = tail->next;
    }
    num_elements++;
  }
};

class Solution {
public:
    ListNode* oddEvenList(ListNode* head) {
        if(head == NULL)return head;
        Linked_List Odds;
        Linked_List Evens;
        ListNode *current = NULL;
        current = head;
        int i = 0;
        while(current){
            if(i%2==0)Odds.push(current->val);
            else Evens.push(current->val);
            i++;
            current = current->next;
        }
        Odds.tail->next = Evens.head;
        return Odds.head;
    }
};