Search Last Kth node in Linked List

last_kth_LL.java

class Node {
    int data;
    Node next;
    Node(int data) {
        this.data = data;
        this.next = null;
    }
}

class Main {
    public static void main(String[] args) {
        Node head = new Node(1);
        insertLast(head, 2);
        insertLast(head, 3);
        insertLast(head, 5);
        head = insertFirst(head, 0);
        insertMiddle(head, 4, 4);
        head = insertFirst(head, -1);
        insertMiddle(head, 6, 6);
        System.out.println("Search Res. : " + searchKLast(head, 5));
        //display(head);
    }
// this is the function your looking for
    public static int searchKLast(Node head, int K) {
        Node fast = head;   // fast pointer
        Node slow = head;   // slow pointer
        while(K > 0) {
            fast = fast.next;  // move fast pointer forward
            K--;
        }
        while(fast!=null) {
            fast = fast.next;
            slow = slow.next;
        }
        return slow.data;  // return data of last k'th node
    }

    public static void insertMiddle(Node head, int val, int position) {
        Node newNode = new Node(val);
        Node temp = head;
        while(temp.next != null && position > 1) {
            position--;
            temp = temp.next;
        }
        Node help = temp.next;
        newNode.next = help;
        temp.next = newNode;
    }

    public static Node insertFirst(Node head, int val) {
        Node newNode = new Node(val);
        newNode.next = head;
        return newNode;
    }

    public static void insertLast(Node head, int val) {
        Node newNode = new Node(val);
        Node temp = head;
        while(temp.next!=null) {
            temp = temp.next;
        }
        temp.next = newNode;
    }


    public static void display(Node head) {
        Node temp = head;

        while(temp!=null){
            System.out.println(temp.data);
            temp = temp.next;
        }
    }
}