30 November Reorder List

class Solution{ 
public:
    Node* reverse(Node* head)
{
    Node* curr = head;
    Node *next = NULL, *prev = NULL;
    while(curr)
    {
        next = curr->next;
        curr->next = prev;
        prev = curr;
        curr = next;
    }
    return prev;
}
Node* merge(Node* a,Node* b)
{
    while(b)
    {
        Node* temp1=a->next;
        Node* temp2=b->next;
        
        a->next=b;
        b->next=temp1;
        a=temp1;
        b=temp2;
    }
    return a;
}
void reorderList(Node* head) 
{
    if(!head || !head->next) return;
    Node *slow = head;
    Node *fast = head->next;
    while(fast&&fast->next)
        {
            slow=slow->next;
            fast=fast->next->next;
        }
    Node* shead = reverse(slow->next);
    slow->next=NULL;
    merge(head,shead);
}
};