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LL_DeleteSingleLLNodeAtGivenPos.java
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LL_DeleteSingleLLNodeAtGivenPos.java
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import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
// https://practice.geeksforgeeks.org/problems/delete-a-node-in-single-linked-list/1
// https://www.geeksforgeeks.org/linked-list-set-3-deleting-node/
// https://www.geeksforgeeks.org/delete-a-linked-list-node-at-a-given-position/
public class LL_DeleteSingleLLNodeAtGivenPos {
public static void main(String[] args) throws IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
int t = Integer.parseInt(br.readLine().trim());
while (t-->0) {
int n = Integer.parseInt(br.readLine().trim());
String str[] = br.readLine().trim().split("\\s+");
int position = Integer.parseInt(br.readLine().trim());
int ip[] = new int[n];
for (int i = 0; i < n; i++) {
ip[i] = Integer.parseInt(str[i]);
}
Node head = buildLinkedList(ip);
System.out.println("Before deletion");
printLinkedList(head);
Node headAfterDeletion = deleteNodeAtGivenPosition(head, position);
printLinkedList(headAfterDeletion);
}
}
private static Node deleteNodeAtGivenPosition(Node head, int position) {
if(head == null) return null;
// if position is 1, then head has to be deleted.
if(position == 1) {
head = head.next;
return head;
}
Node newHead = head;
Node prev = head;
Node toBeDeletedNode = head;
// storing the prev node of to be deleted Node
while(position > 1 && toBeDeletedNode != null) {
prev = toBeDeletedNode;
toBeDeletedNode = toBeDeletedNode.next;
--position;
}
if(toBeDeletedNode != null) prev.next = toBeDeletedNode.next;
return newHead;
}
private static Node buildLinkedList(int[] ip) {
Node head = new Node(ip[0]);
Node tail = head;
for (int i = 1; i < ip.length; i++) {
tail.next = new Node(ip[i]);
tail = tail.next;
}
return head;
}
private static void printLinkedList(Node head) {
StringBuffer sb = new StringBuffer();
Node temp = head;
while(temp != null) {
sb.append(temp.value + " ");
temp = temp.next;
}
System.out.println(sb);
sb.setLength(0);
}
private static final class Node {
private int value;
private Node next;
Node(int value) {
this.value = value;
this.next = null;
}
}
}