反转链表

来源：互联网发布：腾讯阿里云编辑：程序博客网时间：2024/04/29 12:10

方法一：递归版本

C/C++ code



template
<
typename T
>


ListNode
<
T
>*
 reverse_slist_recursive(ListNode
<
T
>*
 head)

{

    
if
 (
!
head
||!
(head
->
next)) 
return
 head;



    ListNode
<
T
>*
 rtn 
=
 reverse_list(head
->
next);



    head
->
next
->
next 
=
 head;

    head
->
next 
=
 NULL;



    
return
 rtn;

}

方法二：利用循环

C/C++ code



template
<
typename T
>


ListNode
<
T
>*
 reverse_slist_common(ListNode
<
T
>*
 head)

{

    
if
 (
!
head
||!
(head
->
next)) 
return
 head;

    

    ListNode
<
T
>
 
*
 prev
=
0
;



    
while
 (head)

    {

        ListNode
<
T
>
 
*
 temp 
=
 head;

        head 
=
 head
->
next;

        temp
->
next 
=
 prev;

        prev 
=
 temp;

    }



    
return
 prev;

}

方法三：利用辅助栈

C/C++ code



template
<
typename T
>


ListNode
<
T
>*
 reverse_slist_usingstack(ListNode
<
T
>*
 head)

{

    
if
 (
!
head
||!
(head
->
next)) 
return
 head;



    ListNode
<
T
>
 
*
prev
=
0
, 
*
pcur
=
0
;

    

    stack
<
ListNode
<
T
>*>
 sl;



    
while
 (head)

    {

        sl.push(head);

        head 
=
 head
->
next;

    }



    head 
=
 pcur 
=
 sl.pop();



    
while
 (
!
sl.empty())

    {

        prev 
=
 sl.pop();

        pcur
->
next 
=
 prev;

        pcur 
=
 prev;

    }



    pcur
->
next 
=
 
0
;



    
return
 head;

}