题目

解决：

import java.util.*;

/*
 * public class ListNode {
 *   int val;
 *   ListNode next = null;
 *   public ListNode(int val) {
 *     this.val = val;
 *   }
 * }
 */

public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param head ListNode类
     * @return ListNode类
     */
    public ListNode ReverseList (ListNode head) {
        // write code here
        ListNode end = null;
        while (head != null) {
            ListNode endNext = null;
            if (end == null) {
                end = new ListNode(head.val);
                end.next = null;
            } else {
                endNext = new ListNode(end.val);
                endNext.next = end.next;
                end.next = endNext;
                end.val = head.val;
            }
            head = head.next;
        }
        return end;
    }
}