how to reverse a linked list in java code example
Example 1: reverse linked list in java to get both head and tail
/*
public class ListNode {
public int val;
public ListNode next;
public ListNode(int x) { val = x; next = null; }
}
*/
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;
}
}
/* Function to reverse the linked list */
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;
}
// prints content of double linked list
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: reverse a linked list
class recursion {
static Node head; // head of list
static class Node {
int data;
Node next;
Node(int d)
{ data = d;
next = null; } }
static Node reverse(Node head)
{
if (head == null || head.next == null)
return head;
/* reverse the rest list and put the first element
at the end */
Node rest = reverse(head.next);
head.next.next = head;
/* tricky step -- see the diagram */
head.next = null;
/* fix the head pointer */
return rest;
} /* Function to print linked list */
static void print()
{
Node temp = head;
while (temp != null) {
System.out.print(temp.data + " ");
temp = temp.next;
}
System.out.println();
}
static void push(int data)
{
Node temp = new Node(data);
temp.next = head;
head = temp;
} /* Driver program to test above function*/
public static void main(String args[])
{
/* Start with the empty list */
push(20);
push(4);
push(15);
push(85);
System.out.println("Given linked list");
print();
head = reverse(head);
System.out.println("Reversed Linked list");
print();
} } // This code is contributed by Prakhar Agarwal
Example 4: 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