reverse a linked list java code example
Example 1: reverse linked list in java to get both head and tail
public static ListNode[] reverse_linked_list(ListNode head) {
ListNode prev = null;
ListNode current = head;
ListNode next;
ListNode tail = head;
while (current != null) {
next = current.next;
current.next = prev;
prev = current;
current = next;
}
head = prev;
ListNode[] result = {head, tail};
return result;
}
Example 2: how to reverse a linked ist
class LinkedList {
static Node head;
static class Node {
int data;
Node next;
Node(int d)
{
data = d;
next = null;
}
}
Node reverse(Node node)
{
Node prev = null;
Node current = node;
Node next = null;
while (current != null) {
next = current.next;
current.next = prev;
prev = current;
current = next;
}
node = prev;
return node;
}
void printList(Node node)
{
while (node != null) {
System.out.print(node.data + " ");
node = node.next;
}
}
public static void main(String[] args)
{
LinkedList list = new LinkedList();
list.head = new Node(85);
list.head.next = new Node(15);
list.head.next.next = new Node(4);
list.head.next.next.next = new Node(20);
System.out.println("Given Linked list");
list.printList(head);
head = list.reverse(head);
System.out.println("");
System.out.println("Reversed linked list ");
list.printList(head);
}
}
Example 3: revese the linked list java
Easiest way
public static LinkedList reverse(LinkedList head) {
LinkedList prevAddress = null;
LinkedList currentAddress = head;
LinkedList nextAddress = head.next;
while(nextAddress!=null) {
currentAddress.next = prevAddress;
prevAddress = currentAddress;
currentAddress = nextAddress;
nextAddress= currentAddress.next;
currentAddress.next = prevAddress;
}
head = currentAddress;
return head;
}
Just try to visualize its all about pointers game. :-)
NO GFG ANSWER