how to reverse a linked list 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: 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 3: reverse linkedlist
Collections.reverse(list);