Binary Search on Singly Linked List

// C# code to implement binary search
// on Singly Linked List
using System;

class Node {
    public int Data;
    public Node next;

    public Node(int x) {
        Data = x;
        next = null;
    }
}

class GfG {

    // function to find out middle element
    static Node Middle(Node start, Node last) {
        if (start == null) {
            return null;
        }

        if (start == last) {
            return start;
        }

        Node slow = start;
        Node fast = start.next;

        while (fast != last) {
            fast = fast.next;
            slow = slow.next;
            if (fast != last) {
                fast = fast.next;
            }
        }

        return slow;
    }

    // Function for implementing the Binary
    // Search on linked list
    static bool BinarySearch(Node head, int value) {
        Node start = head;
        Node last = null;

        while (true) {

            // Find middle
            Node mid = Middle(start, last);

            // If middle is empty
            if (mid == null) {
                return false;
            }

            // If value is present at middle
            if (mid.Data == value) {
                return true;
            }

            // If start and last node are overlapping
            else if (start == last) {
                break;
            }

            // If value is more than mid
            else if (mid.Data < value) {
                start = mid.next;
            }

            // If the value is less than mid.
            else if (mid.Data > value) {
                last = mid;
            }
        }

        // value not present
        return false;
    }

    static void Main() {

        // Create a hard-coded linked list:
        // 1 -> 4 -> 7 -> 8 -> 9 -> 10
        Node head = new Node(1);
        head.next = new Node(4);
        head.next.next = new Node(7);
        head.next.next.next = new Node(8);
        head.next.next.next.next = new Node(9);
        head.next.next.next.next.next = new Node(10);

        int value = 7;
        if (BinarySearch(head, value)) {
            Console.WriteLine("Present");
        }
        else {
            Console.WriteLine("Value not present");
        }
    }
}