Objective: Given a Linked List and x and y. Delete x number of nodes after y nodes from the start.
Example:
->10->20->30->40->50->60->70->80->90->100->110->120 Deleted 4 Nodes after 5 Nodes ->10->20->30->40->50->100->110->120
Approach:
- We need two pointers.
- One pointer at one node prior to the nodes to be deleted. ( Move it by y starting from the head).
- Another pointer at one node after to the nodes to be deleted. (Move it by x starting from the y, as per previous step).
- Then Just link these two nodes.
Complete Code:
| public class DeleteYNodesAfterXNodes { | |
| public int len; | |
| public Node head; | |
| public DeleteYNodesAfterXNodes() { | |
| head = null; | |
| } | |
| public void deleteYAfterX(int x, int y) { | |
| len = getLength(head); | |
| if (x >= len) { | |
| System.out.println("\nINVALID NUMBER"); | |
| return; | |
| } | |
| Node n = head; | |
| while (x > 1) {// since we need to one node prior before we start | |
| // deleting | |
| n = n.next; | |
| x—; | |
| } | |
| Node temp = n; | |
| // System.out.println("\n" + temp.data); | |
| y = y + 1; // since we need the node, after deleting y nodes | |
| while (y > 0 && n != null) { | |
| n = n.next; | |
| y—; | |
| } | |
| temp.next = n; | |
| } | |
| public int getLength(Node head) { | |
| Node n = head; | |
| int count = 0; | |
| while (n != null) { | |
| n = n.next; | |
| count++; | |
| } | |
| return count; | |
| } | |
| public void addNodeAtEnd(int data) { | |
| Node n = new Node(data); | |
| if (head == null) { | |
| n.next = head; | |
| head = n; | |
| } else { | |
| Node currNode = head; | |
| while (currNode.next != null) { | |
| // System.out.print("—->" + currNode.data); | |
| currNode = currNode.next; | |
| } | |
| currNode.next = n; | |
| } | |
| } | |
| public void display() { | |
| // System.out.println(""); | |
| Node currNode = head; | |
| while (currNode != null) { | |
| System.out.print("->" + currNode.data); | |
| currNode = currNode.next; | |
| } | |
| } | |
| public static void main(String[] args) throws java.lang.Exception { | |
| DeleteYNodesAfterXNodes a = new DeleteYNodesAfterXNodes(); | |
| a.addNodeAtEnd(10); | |
| a.addNodeAtEnd(20); | |
| a.addNodeAtEnd(30); | |
| a.addNodeAtEnd(40); | |
| a.addNodeAtEnd(50); | |
| a.addNodeAtEnd(60); | |
| a.addNodeAtEnd(70); | |
| a.addNodeAtEnd(80); | |
| a.addNodeAtEnd(90); | |
| a.addNodeAtEnd(100); | |
| a.addNodeAtEnd(110); | |
| a.addNodeAtEnd(120); | |
| a.display(); | |
| a.deleteYAfterX(5, 4); | |
| System.out.println("\nDeleted 4 Nodes after 5 Nodes"); | |
| a.display(); | |
| } | |
| } | |
| class Node { | |
| public int data; | |
| public Node next; | |
| public Node(int data) { | |
| this.data = data; | |
| this.next = null; | |
| } | |
| } |
Output:
->10->20->30->40->50->60->70->80->90->100->110->120 Deleted 4 Nodes after 5 Nodes ->10->20->30->40->50->100->110->120