# Delete N nodes after M nodes of a linked list

Given a linked list and two integers M and N. Traverse the linked list such that you retain M nodes then delete next N nodes, continue the same till end of the linked list.

Difficulty Level: Rookie

Examples:

```Input:
M = 2, N = 2
Output:

Input:
M = 3, N = 2
Output:

Input:
M = 1, N = 1
Output:

## Recommended: Please solve it on “PRACTICE” first, before moving on to the solution.

The main part of the problem is to maintain proper links between nodes, make sure that all corner cases are handled. Following is C implementation of function skipMdeleteN() that skips M nodes and delete N nodes till end of list. It is assumed that M cannot be 0.

## C++

 `// C++ program to delete N nodes ` `// after M nodes of a linked list  ` `#include ` `using` `namespace` `std; ` ` `  `// A linked list node  ` `class` `Node  ` `{  ` `    ``public``: ` `    ``int` `data;  ` `    ``Node *next;  ` `};  ` ` `  `/* Function to insert a node at the beginning */` `void` `push(Node ** head_ref, ``int` `new_data)  ` `{  ` `    ``/* allocate node */` `    ``Node* new_node = ``new` `Node(); ` ` `  `    ``/* put in the data */` `    ``new_node->data = new_data;  ` ` `  `    ``/* link the old list off the new node */` `    ``new_node->next = (*head_ref);  ` ` `  `    ``/* move the head to point to the new node */` `    ``(*head_ref) = new_node;  ` `}  ` ` `  `/* Function to print linked list */` `void` `printList(Node *head)  ` `{  ` `    ``Node *temp = head;  ` `    ``while` `(temp != NULL)  ` `    ``{  ` `        ``cout<data<<``" "``;  ` `        ``temp = temp->next;  ` `    ``}  ` `    ``cout<next;  ` ` `  `        ``// If we reached end of list, then return  ` `        ``if` `(curr == NULL)  ` `            ``return``;  ` ` `  `        ``// Start from next node and delete N nodes  ` `        ``t = curr->next;  ` `        ``for` `(count = 1; count<=N && t!= NULL; count++)  ` `        ``{  ` `            ``Node *temp = t;  ` `            ``t = t->next;  ` `            ``free``(temp);  ` `        ``}  ` `         `  `        ``// Link the previous list with remaining nodes  ` `        ``curr->next = t;  ` ` `  `        ``// Set current pointer for next iteration  ` `        ``curr = t;  ` `    ``}  ` `}  ` ` `  `// Driver code  ` `int` `main()  ` `{  ` `    ``/* Create following linked list  ` `    ``1->2->3->4->5->6->7->8->9->10 */` `    ``Node* head = NULL;  ` `    ``int` `M=2, N=3;  ` `    ``push(&head, 10);  ` `    ``push(&head, 9);  ` `    ``push(&head, 8);  ` `    ``push(&head, 7);  ` `    ``push(&head, 6);  ` `    ``push(&head, 5);  ` `    ``push(&head, 4);  ` `    ``push(&head, 3);  ` `    ``push(&head, 2);  ` `    ``push(&head, 1);  ` ` `  `    ``cout << ``"M = "` `<< M<< ``" N = "` `<< N << ``"\nGiven Linked list is :\n"``;  ` `    ``printList(head);  ` ` `  `    ``skipMdeleteN(head, M, N);  ` ` `  `    ``cout<<``"\nLinked list after deletion is :\n"``;  ` `    ``printList(head);  ` ` `  `    ``return` `0;  ` `}  ` ` `  `// This code is contributed by rathbhupendra `

## C

 `// C program to delete N nodes after M nodes of a linked list ` `#include ` `#include ` ` `  `// A linked list node ` `struct` `Node ` `{ ` `    ``int` `data; ` `    ``struct` `Node *next; ` `}; ` ` `  `/* Function to insert a node at the beginning */` `void` `push(``struct` `Node ** head_ref, ``int` `new_data) ` `{ ` `    ``/* allocate node */` `    ``struct` `Node* new_node = (``struct` `Node*) ``malloc``(``sizeof``(``struct` `Node)); ` ` `  `    ``/* put in the data  */` `    ``new_node->data  = new_data; ` ` `  `    ``/* link the old list off the new node */` `    ``new_node->next = (*head_ref); ` ` `  `    ``/* move the head to point to the new node */` `    ``(*head_ref)  = new_node; ` `} ` ` `  `/* Function to print linked list */` `void` `printList(``struct` `Node *head) ` `{ ` `    ``struct` `Node *temp = head; ` `    ``while` `(temp != NULL) ` `    ``{ ` `        ``printf``(``"%d "``, temp->data); ` `        ``temp = temp->next; ` `    ``} ` `    ``printf``(``"\n"``); ` `} ` ` `  `// Function to skip M nodes and then delete N nodes of the linked list. ` `void` `skipMdeleteN(``struct` `Node  *head, ``int` `M, ``int` `N) ` `{ ` `    ``struct` `Node *curr = head, *t; ` `    ``int` `count; ` ` `  `    ``// The main loop that traverses through the whole list ` `    ``while` `(curr) ` `    ``{ ` `        ``// Skip M nodes ` `        ``for` `(count = 1; countnext; ` ` `  `        ``// If we reached end of list, then return ` `        ``if` `(curr == NULL) ` `            ``return``; ` ` `  `        ``// Start from next node and delete N nodes ` `        ``t = curr->next; ` `        ``for` `(count = 1; count<=N && t!= NULL; count++) ` `        ``{ ` `            ``struct` `Node *temp = t; ` `            ``t = t->next; ` `            ``free``(temp); ` `        ``} ` `        ``curr->next = t; ``// Link the previous list with remaining nodes ` ` `  `        ``// Set current pointer for next iteration ` `        ``curr = t; ` `    ``} ` `} ` ` `  `// Driver program to test above functions ` `int` `main() ` `{ ` `    ``/* Create following linked list ` `      ``1->2->3->4->5->6->7->8->9->10 */` `    ``struct` `Node* head = NULL; ` `    ``int` `M=2, N=3; ` `    ``push(&head, 10); ` `    ``push(&head, 9); ` `    ``push(&head, 8); ` `    ``push(&head, 7); ` `    ``push(&head, 6); ` `    ``push(&head, 5); ` `    ``push(&head, 4); ` `    ``push(&head, 3); ` `    ``push(&head, 2); ` `    ``push(&head, 1); ` ` `  `    ``printf``(``"M = %d, N = %d \nGiven Linked list is :\n"``, M, N); ` `    ``printList(head); ` ` `  `    ``skipMdeleteN(head, M, N); ` ` `  `    ``printf``(``"\nLinked list after deletion is :\n"``); ` `    ``printList(head); ` ` `  `    ``return` `0; ` `} `

## Java

 `// Java program to delete N nodes  ` `// after M nodes of a linked list  ` `import` `java.util.*; ` ` `  `class` `GFG ` `{ ` ` `  `// A linked list node  ` `static` `class` `Node  ` `{  ` `    ``int` `data;  ` `    ``Node next;  ` `};  ` ` `  `/* Function to insert a node at the beginning */` `static` `Node push( Node head_ref, ``int` `new_data)  ` `{  ` `    ``/* allocate node */` `    ``Node new_node = ``new` `Node();  ` ` `  `    ``/* put in the data */` `    ``new_node.data = new_data;  ` ` `  `    ``/* link the old list off the new node */` `    ``new_node.next = (head_ref);  ` ` `  `    ``/* move the head to point to the new node */` `    ``(head_ref) = new_node; ` `     `  `    ``return` `head_ref; ` `}  ` ` `  `/* Function to print linked list */` `static` `void` `printList( Node head)  ` `{  ` `    ``Node temp = head;  ` `    ``while` `(temp != ``null``)  ` `    ``{  ` `        ``System.out.printf(``"%d "``, temp.data);  ` `        ``temp = temp.next;  ` `    ``}  ` `    ``System.out.printf(``"\n"``);  ` `}  ` ` `  `// Function to skip M nodes and then ` `// delete N nodes of the linked list.  ` `static` `void` `skipMdeleteN( Node head, ``int` `M, ``int` `N)  ` `{  ` `    ``Node curr = head, t;  ` `    ``int` `count;  ` ` `  `    ``// The main loop that traverses ` `    ``// through the whole list  ` `    ``while` `(curr!=``null``)  ` `    ``{  ` `        ``// Skip M nodes  ` `        ``for` `(count = ``1``; count < M && curr != ``null``; count++)  ` `            ``curr = curr.next;  ` ` `  `        ``// If we reached end of list, then return  ` `        ``if` `(curr == ``null``)  ` `            ``return``;  ` ` `  `        ``// Start from next node and delete N nodes  ` `        ``t = curr.next;  ` `        ``for` `(count = ``1``; count <= N && t != ``null``; count++)  ` `        ``{  ` `            ``Node temp = t;  ` `            ``t = t.next;  ` `        ``}  ` `         `  `        ``// Link the previous list with remaining nodes  ` `        ``curr.next = t;  ` ` `  `        ``// Set current pointer for next iteration  ` `        ``curr = t;  ` `    ``}  ` `}  ` ` `  `// Driver code  ` `public` `static` `void` `main(String args[]) ` `{  ` `    ``/* Create following linked list  ` `    ``1.2.3.4.5.6.7.8.9.10 */` `    ``Node head = ``null``;  ` `    ``int` `M=``2``, N=``3``;  ` `    ``head=push(head, ``10``);  ` `    ``head=push(head, ``9``);  ` `    ``head=push(head, ``8``);  ` `    ``head=push(head, ``7``);  ` `    ``head=push(head, ``6``);  ` `    ``head=push(head, ``5``);  ` `    ``head=push(head, ``4``);  ` `    ``head=push(head, ``3``);  ` `    ``head=push(head, ``2``);  ` `    ``head=push(head, ``1``);  ` ` `  `    ``System.out.printf(``"M = %d, N = %d \nGiven"` `+  ` `                        ``"Linked list is :\n"``, M, N);  ` `    ``printList(head);  ` ` `  `    ``skipMdeleteN(head, M, N);  ` ` `  `    ``System.out.printf(``"\nLinked list after deletion is :\n"``);  ` `    ``printList(head);  ` `}  ` `} ` ` `  `// This code is contributed by Arnab Kundu `

## Python

 `# Python program to delete M nodes after N nodes ` ` `  `# Node class  ` `class` `Node: ` ` `  `    ``# Constructor to initialize the node object ` `    ``def` `__init__(``self``, data): ` `        ``self``.data ``=` `data ` `        ``self``.``next` `=` `None` ` `  `class` `LinkedList: ` ` `  `    ``# Function to initialize head ` `    ``def` `__init__(``self``): ` `        ``self``.head ``=` `None` ` `  `    ``# Function to insert a new node at the beginning ` `    ``def` `push(``self``, new_data): ` `        ``new_node ``=` `Node(new_data) ` `        ``new_node.``next` `=` `self``.head ` `        ``self``.head ``=` `new_node ` ` `  `    ``# Utility function to prit the linked LinkedList ` `    ``def` `printList(``self``): ` `        ``temp ``=` `self``.head ` `        ``while``(temp): ` `            ``print` `temp.data, ` `            ``temp ``=` `temp.``next` ` `  `    ``def` `skipMdeleteN(``self``, M, N): ` `        ``curr ``=` `self``.head ` `         `  `        ``# The main loop that traverses through the ` `        ``# whole list ` `        ``while``(curr): ` `            ``# Skip M nodes ` `            ``for` `count ``in` `range``(``1``, M): ` `                ``if` `curr ``is` `None``: ` `                    ``return`  `                ``curr ``=` `curr.``next` `                     `  `            ``if` `curr ``is` `None` `: ` `                ``return`  ` `  `            ``# Start from next node and delete N nodes ` `            ``t ``=` `curr.``next`  `            ``for` `count ``in` `range``(``1``, N``+``1``): ` `                ``if` `t ``is` `None``: ` `                    ``break` `                ``t ``=` `t.``next` `     `  `            ``# Link the previous list with reamining nodes ` `            ``curr.``next` `=` `t ` `            ``# Set Current pointer for next iteration ` `            ``curr ``=` `t  ` ` `  `# Driver program to test above function ` ` `  `# Create following linked list ` `# 1->2->3->4->5->6->7->8->9->10 ` `llist ``=` `LinkedList() ` `M ``=` `2`  `N ``=` `3` `llist.push(``10``) ` `llist.push(``9``) ` `llist.push(``8``) ` `llist.push(``7``) ` `llist.push(``6``) ` `llist.push(``5``) ` `llist.push(``4``) ` `llist.push(``3``) ` `llist.push(``2``) ` `llist.push(``1``) ` ` `  `print` `"M = %d, N = %d\nGiven Linked List is:"` `%``(M, N) ` `llist.printList() ` `print`  ` `  `llist.skipMdeleteN(M, N) ` ` `  `print` `"\nLinked list after deletion is"` `llist.printList() ` ` `  `# This code is contributed by Nikhil Kumar Singh(nickzuck_007) `

## C#

 `// C# program to delete N nodes  ` `// after M nodes of a linked list  ` `using` `System; ` ` `  `class` `GFG  ` `{  ` ` `  `// A linked list node  ` `public` `class` `Node  ` `{  ` `    ``public` `int` `data;  ` `    ``public` `Node next;  ` `};  ` ` `  `/* Function to insert a node at the beginning */` `static` `Node push( Node head_ref, ``int` `new_data)  ` `{  ` `    ``/* allocate node */` `    ``Node new_node = ``new` `Node();  ` ` `  `    ``/* put in the data */` `    ``new_node.data = new_data;  ` ` `  `    ``/* link the old list off the new node */` `    ``new_node.next = (head_ref);  ` ` `  `    ``/* move the head to point to the new node */` `    ``(head_ref) = new_node;  ` `     `  `    ``return` `head_ref;  ` `}  ` ` `  `/* Function to print linked list */` `static` `void` `printList( Node head)  ` `{  ` `    ``Node temp = head;  ` `    ``while` `(temp != ``null``)  ` `    ``{  ` `        ``Console.Write(``"{0} "``, temp.data);  ` `        ``temp = temp.next;  ` `    ``}  ` `    ``Console.Write(``"\n"``);  ` `}  ` ` `  `// Function to skip M nodes and then  ` `// delete N nodes of the linked list.  ` `static` `void` `skipMdeleteN( Node head, ``int` `M, ``int` `N)  ` `{  ` `    ``Node curr = head, t;  ` `    ``int` `count;  ` ` `  `    ``// The main loop that traverses  ` `    ``// through the whole list  ` `    ``while` `(curr!=``null``)  ` `    ``{  ` `        ``// Skip M nodes  ` `        ``for` `(count = 1; count < M &&  ` `                ``curr != ``null``; count++)  ` `            ``curr = curr.next;  ` ` `  `        ``// If we reached end of list, then return  ` `        ``if` `(curr == ``null``)  ` `            ``return``;  ` ` `  `        ``// Start from next node and delete N nodes  ` `        ``t = curr.next;  ` `        ``for` `(count = 1; count <= N && t != ``null``; count++)  ` `        ``{  ` `            ``Node temp = t;  ` `            ``t = t.next;  ` `        ``}  ` `         `  `        ``// Link the previous list with remaining nodes  ` `        ``curr.next = t;  ` ` `  `        ``// Set current pointer for next iteration  ` `        ``curr = t;  ` `    ``}  ` `}  ` ` `  `// Driver code  ` `public` `static` `void` `Main(String []args)  ` `{  ` `    ``/* Create following linked list  ` `    ``1.2.3.4.5.6.7.8.9.10 */` `    ``Node head = ``null``;  ` `    ``int` `M=2, N=3;  ` `    ``head=push(head, 10);  ` `    ``head=push(head, 9);  ` `    ``head=push(head, 8);  ` `    ``head=push(head, 7);  ` `    ``head=push(head, 6);  ` `    ``head=push(head, 5);  ` `    ``head=push(head, 4);  ` `    ``head=push(head, 3);  ` `    ``head=push(head, 2);  ` `    ``head=push(head, 1);  ` ` `  `    ``Console.Write(``"M = {0}, N = {1} \nGiven"` `+  ` `                        ``"Linked list is :\n"``, M, N);  ` `    ``printList(head);  ` ` `  `    ``skipMdeleteN(head, M, N);  ` ` `  `    ``Console.Write(``"\nLinked list after deletion is :\n"``);  ` `    ``printList(head);  ` `}  ` `}  ` ` `  `// This code contributed by Rajput-Ji `

Output:

```M = 2, N = 3
1 2 3 4 5 6 7 8 9 10

Linked list after deletion is :
1 2 6 7```

Time Complexity: O(n) where n is number of nodes in linked list.

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