劍指offer 反轉鏈表

題目詳情

輸入一個鏈表，反轉鏈表後，輸出新鏈表的表頭。

代碼

/*
public class ListNode {
    int val;
    ListNode next = null;
 
    ListNode(int val) {
        this.val = val;
    }
}*/
public class Solution {
    public ListNode ReverseList(ListNode head) {
        if(head == null){
            return null;
        }
        ListNode res = head;
        if(head.next == null){
            return res;
        }else{
            head = head.next;
            res.next = null;
            while(head != null){
                ListNode temp = head;
                head = head.next;
                temp.next = res;
                res = temp;
            }
        }
        return res;
         
         
    }
}