Reversing Singly Linked List Easily

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Oct 18th, 2007

Views: 3,270

jai_steave

This will works Recusivly and easily

Last edited : Oct 18th, 2007.

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c Syntax |

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void rev(node *h,node *myparentaddr)
{
if(h->next!=NULL)
{
rev(h->next,h);
tail=h;
}
else
head=h;
h->next=myparentaddr;
}
 
call it in main by rev(head,NULL);

Comments (Newest First)

jessel | Newbie Poster | Feb 26th, 2008

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hello do you have a program in c that deals in linked list?
please help me

farwa | Newbie Poster | Feb 7th, 2008

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hello every one i m new to c language can any one help me in typing a marksheet in c.

Duoas | Posting Virtuoso | Nov 9th, 2007

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Nice, but it fails on three counts:
1. It doesn't return the new head of the list.
2. It fails if h is NULL.
3. It fails on really big lists (stack overflow).

Here's an iterative solution you might enjoy.

 Help with Code Tags 
 C Syntax (Toggle Plain Text) 
/*
  Reverse a singly linked list without recursion.
  The argument may be NULL.
  Returns the new head of the list.
  Runs in linear time and with constant memory usage.
 */
node *rev( node *head ) {
  node *next;
  node *curr = head;
  node *prev = NULL;
 
  while (curr != NULL) {
    next       = curr->next;
    curr->next = prev;
 
    prev       = curr;
    curr       = next;
    }
 
  return prev;
  }
/*
  Reverse a singly linked list without recursion.
  The argument may be NULL.
  Returns the new head of the list.
  Runs in linear time and with constant memory usage.
 */
node *rev( node *head ) {
  node *next;
  node *curr = head;
  node *prev = NULL;

  while (curr != NULL) {
    next       = curr->next;
    curr->next = prev;

    prev       = curr;
    curr       = next;
    }

  return prev;
  }

Call it thus:
head = rev( head );

Enjoy!

jai_steave | Newbie Poster | Oct 18th, 2007

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it works recursively

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Reversing Singly Linked List Easily