反转链表——java

给定一个链表，请你将链表反转过来。

举例：原链表：1→2→3→4→5→null

反转链表：5→4→3→2→1→null

代码:

package algorithm_niuke;

public class Main {
    public static Node reverseList(Node head) {
        if(head == null) {
            return head;
        }

        Node pre = null;
        Node next = null;

        while(head!=null) {
            next = head.next;
            head.next = pre;
            pre = head;
            head = next;
        }

        return pre;
    }

    private static class Node {
        int val;
        Node next;

        public Node(int val) {
            this.val = val;
        }
    }

    public static void main(String[] args) {

    }
}