GFG PTOD | 25 Jan | Find the first node of loop in linked list

Node* findFirstNode(Node* head) {
        // your code here
        Node* slow = head, *fast = head;
        while(fast && fast->next) {
            slow = slow->next;
            fast = fast->next->next;
            if(slow == fast) {
                slow = head;
                while(slow!=fast) {
                    slow = slow->next;
                    fast = fast->next;
                }
                return slow;
            }
        }
        return NULL;
    }