import java.util.*;

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

public class Solution {
    /**
     * 代碼中的類名、方法名、參數(shù)名已經(jīng)指定，請(qǐng)勿修改，直接返回方法規(guī)定的值即可
     *
     * 
     * @param head ListNode類 
     * @return ListNode類
     */
    public ListNode ReverseList (ListNode head) {
        // write code here
        ListNode pre = null;
        ListNode cur  = head;
        while(cur!=null){
            ListNode temp = cur;
            cur = cur.next;
            temp.next = pre;
            pre = temp;
        }
        return pre;
    }
}