Leetcode/src/main/java/com/fishercoder/solutions/_206.java at master · ernestp56/Leetcode · GitHub

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package com.fishercoder.solutions;

import com.fishercoder.common.classes.ListNode;

public class _206 {

    public static class Solution1 {
        public ListNode reverseList(ListNode head) {
            ListNode newHead = null;
            while (head != null) {
                ListNode next = head.next;
                head.next = newHead;
                newHead = head;
                head = next;
            }
            return newHead;
        }
    }

    public static class Solution2 {
        public ListNode reverseList(ListNode head) {
            return reverse(head, null);
        }

        ListNode reverse(ListNode head, ListNode newHead) {
            if (head == null) {
                return newHead;
            }
            ListNode next = head.next;
            head.next = newHead;
            newHead = head;
            head = next;
            return reverse(head, newHead);
        }
    }

}