题解 | #反转链表#

import java.util.*;


 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 = new ListNode(0);
        ListNode cur = head;
        ListNode temp = null;
        if(cur == null || cur.next == null){
            return cur;
        }
        newHead.next = cur;
        cur = cur.next;
        newHead.next.next = null;

        while(cur != null){
        temp = cur;
        cur = cur.next;
        temp.next = newHead.next;
        newHead.next = temp;
}
        return newHead.next;
    }
    public static void main(String args[]){

    }
}