单向链表反转一般有两种实现思路：
- 循环遍历
- 递归
代码如下：
package constxiong.interview;import constxiong.interview.SingleLinkedList.Node;/** * 反转单向列表 * * @author ConstXiong * @date 2019-11-06 11:04:12 */public class TestReserveLinkedList {public static void main(String[] args) {SingleLinkedList<Integer> ll = new SingleLinkedList<Integer>();ll.add(1);ll.add(2);ll.add(3);ll.add(4);ll.add(5);ll.print();reverseLinkedList(ll);System.out.println();ll.print();}public static void reverseLinkedList(SingleLinkedList<Integer> ll) {Node<Integer> first = ll.first;reverseNode(first);//reverseNodeByRecursion(first);ll.first = ll.last;ll.last = first;}/** * 循环逆转节点指针 * @param first */public static void reverseNode(Node<Integer> first) {Node<Integer> pre = null;Node<Integer> next = null;while (first != null) {next = first.next;first.next = pre;pre = first;first = next;}}/** * 递归逆转节点指针 * @param head * @return */public static Node<Integer> reverseNodeByRecursion(Node<Integer> first) {if (first == null || first.next == null) {return first;}Node<Integer> prev = reverseNodeByRecursion(first.next);first.next.next = first;first.next = null;return prev;}}