题解 | #反转链表#

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 node = new ListNode(0);
        while (head != null) {
            if (head != null) {
                ListNode lsNode = new ListNode(0);
                lsNode = head;
                head = head.next;
                lsNode.next = node.next;
                node.next = lsNode;
            } else {
                node.next = head;
                head = head.next;
            }
        }
        return node.next;
    }
}

循环遍历链表，遍历的时候，创建新链表，然后从头部插入。