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 newHead = null;
    while(head != null){
    //临时链表放入下次原链表访问的值
        ListNode temp = head.next;
    //原链表的下一个引用为新链表的引用
        head.next = newHead;  
        newHead = head;
        head = temp;

    }
    return newHead;
    }
}