DeleteeveryNnodes.java

// Delete every N nodes
// Send Feedback
// You have been given a singly linked list of integers along with two integers,
// 'M,' and 'N.' Traverse the linked list such that you retain the 'M' nodes,
// then delete the next 'N' nodes. Continue the same until the end of the linked
// list. Indexing starts from 1.
// To put it in other words, in the given linked list, you need to delete N
// nodes after every M nodes.
// Note :
// No need to print the list, it has already been taken care. Only return the
// new head to the list. You can return null in case where all nodes will be
// deleted.
// Input format :
// The first line contains an Integer 't' which denotes the number of test cases
// or queries to be run. Then the test cases follow.

// The first line of each test case or query contains the elements of the singly
// linked list separated by a single space.

// The second line of input contains two integer values 'M,' and 'N,'
// respectively. A single space will separate them.
// Remember/Consider :
// While specifying the list elements for input, -1 indicates the end of the
// singly linked list and hence, would never be a list element
// Output format :
// For each test case/query, print the elements of the updated singly linked
// list.

// Output for every test case will be printed in a seperate line.
// Constraints :
// 1 <= t <= 10^2
// 0 <= P <= 10^5
// Where P is the size of the singly linked list.
// 0 <= M <= 10^5
// 0 <= N <= 10^5

// Time Limit: 1sec
// Sample Input 1 :
// 1
// 1 2 3 4 5 6 7 8 -1
// 2 2
// Sample Output 1 :
// 1 2 5 6
// Sample Input 2 :
// 2
// 10 20 30 40 50 60 -1
// 0 1
// 1 2 3 4 5 6 7 8 -1
// 2 3
// Sample Output 2 :
// 1 2 6 7
// Explanation of Sample Input 2 :
// For the first query, we delete one node after every zero elements hence
// removing all the items of the list. Therefore, nothing got printed.

// For the second query, we delete three nodes after every two nodes, resulting
// in the final list, 1 -> 2 -> 6 -> 7.

/*

    Following is the Node class already written for the Linked List

    class Node<T> {
        T data;
        Node<T> next;
    
        public Node(T data) {
            this.data = data;
        }
    }

*/

class Solution {

    public static Node<Integer> skipMdeleteN(Node<Integer> head, int M, int N) {
        // Your code goes here
        if (head == null) {
            return head;
        }
        if (M == 0) {
            return null;
        }

        Node<Integer> temp = head;
        int deleteNum = N;
        int count = 1;
        while (temp != null) {
            if (count == M) {
                while (deleteNum != 0 && temp.next != null) {
                    temp.next = temp.next.next;
                    deleteNum--;
                }
                count = 0;
                deleteNum = N;
            }

            temp = temp.next;
            count++;
        }

        return head;
    }
}