package main
import . "nc_tools"
/*
 * type ListNode struct{
 *   Val int
 *   Next *ListNode
 * }
 */

/**
 * 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
*/
func ReverseList( head *ListNode ) *ListNode {
    ans := ListNode{Val: -1, Next: nil}
    for head != nil {
        head_next := head.Next
        ans_next := ans.Next
        ans.Next = head
        head.Next = ans_next
        head = head_next
    }
    return ans.Next
}