Reverse LinkedList in Groups of K

Problem Statement

Reverse a Linked List in groups of given size. | Practice | GeeksforGeeks Pattern:

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Solution

Node successor;
 
Node reverseN (Node head, int k) {
	if(head.next== null || k == 1) {
		successor = head.next;
		return head;
	}
	
	Node newHead = reverseN (head.next, k-1);
	head.next.next= head;                   // point next to self
	head.next = null;                       // point self to null
	
	return newHead;
}
 
Node reverse(Node head, int k)
{
	Node dummy = new Node(-1), dummyHead = dummy;
	dummy.next = head; successor = head;
	
	while(dummy != null && successor != null) {
		dummy.next = reverseN(successor, k);
		for (int i = 0 ; i < k && dummy != null; i++) dummy = dummy.next;
	}
	
	return dummyHead.next;
}

Notes