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help me to explain this recursive code

 
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help me to explain this recursive code, reversing a linked list backwards
EquinoX
16 Feb, 2008 - 08:45 AM
Post #1

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here's the code:

CODE

node reverse(head)
{
if(head->next == NULL) /*last element, base case*/
{
  temp = head;
}

else
{
    temp = reverse (head->next);  /*Recursive Call on the remaining elements*/
    head->next->next = head;  /*Put the first element at the end */
    head->next = NULL;
}


what I don't understand is that after it reaches the base case,say that I have this linked list

1 --> 3 --> 5 -- > 7

the recursion goes like this

3-->5-->7

and then

5-->7

and

7

then after it reaches 7 it hits the base case, however I don't understand what head.next.next does and why's head.next == NULL. can someoene explain me this?? Thanks
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Martyr2
RE: Help Me To Explain This Recursive Code
16 Feb, 2008 - 09:22 AM
Post #2

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I couldn't tell you because...

A.) This is not valid Java at all. The syntax even looks more like C++
B.) It is missing a lot of things including return statements, how temp is playing a part in this and see how "head" changes (if it does).

It is an incomplete example and you could only guess what is going on based on what you have provided. Perhaps you can clean it up a bit and actually give us a good java example.

Thanks! smile.gif
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EquinoX
RE: Help Me To Explain This Recursive Code
16 Feb, 2008 - 10:37 AM
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QUOTE(Martyr2 @ 16 Feb, 2008 - 10:22 AM) *

I couldn't tell you because...

A.) This is not valid Java at all. The syntax even looks more like C++
B.) It is missing a lot of things including return statements, how temp is playing a part in this and see how "head" changes (if it does).

It is an incomplete example and you could only guess what is going on based on what you have provided. Perhaps you can clean it up a bit and actually give us a good java example.

Thanks! smile.gif



yeah it's actually only the pseudocode.. I am just trying to understand the concept first
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