Reorder List [LeetCode]

Given a singly linked list L: L0→L1→…→Ln-1→Ln,
reorder it to: L0→Ln→L1→Ln-1→L2→Ln-2→…

You must do this in-place without altering the nodes' values.

For example,
Given {1,2,3,4}, reorder it to {1,4,2,3}.

Solution: make sure the last element points to NULL in the new list;

     void reorderList(ListNode *head) {
         vector<ListNode * > nodes;
         ListNode * current = head;
         while(current != NULL) {
             nodes.push_back(current);
             current = current->next;
         }
         for(int i = ; i < nodes.size() / ; i ++){
             int next = nodes.size() -  - i;
             if(i < next){
                 ListNode * tmp = nodes[i]->next;
                 nodes[i]->next = nodes[next];
                 nodes[next]->next = tmp;
             }
         }
         if(nodes.size() > )
             nodes[nodes.size() / ]->next = NULL;
     }

     void reorderList(ListNode *head) {
         vector<ListNode * > nodes;
         ListNode * current = head;
         while(current != NULL) {
             nodes.push_back(current);
             current = current->next;
         }
         for(int i = ; i < nodes.size() / ; i ++){
             if(i < nodes.size() -  - i){
                 nodes[i]->next = nodes[nodes.size() -  - i];
                 if(i +  < nodes.size() -  - i)
                     nodes[nodes.size() -  - i]->next = nodes[i + ];
                 else
                     nodes[nodes.size() -  - i]->next = NULL;
             }
         }
         if(nodes.size() %  == )
             nodes[nodes.size() / ]->next = NULL;
     }