01_ReverseLinkedList.java

// Problem: Reverse a Linked List
// Author: Ataul (codeByunique)

class ListNode {
    int val;
    ListNode next;

    ListNode(int val) {
        this.val = val;
    }
}

class ReverseLinkedList {
    public static void main(String[] args) {
        // Creating Linked List: 1 → 2 → 3 → 4 → 5
        ListNode head = new ListNode(1);
        head.next = new ListNode(2);
        head.next.next = new ListNode(3);
        head.next.next.next = new ListNode(4);
        head.next.next.next.next = new ListNode(5);

        ListNode reversed = reverseList(head);

        // Print reversed list
        System.out.print("Reversed List: ");
        while (reversed != null) {
            System.out.print(reversed.val + " ");
            reversed = reversed.next;
        }
    }

    public static ListNode reverseList(ListNode head) {
        ListNode prev = null;
        ListNode current = head;

        while (current != null) {
            ListNode nextTemp = current.next;
            current.next = prev;
            prev = current;
            current = nextTemp;
        }

        return prev;
    }
}