Please Help! recursive call

[pot tom]

Sorry for posting here, badly I need help from expert like you!

Can any one explain why my codes does works properly, I mean result what I am suppose to get, it not getting through this method. This is just two method. from my class "MainClass.java".

 
 
public static IntNode difference(IntNode head1, IntNode head2)
{
if(head1==null && head2==null) return null; 
if(head1==null) return null;
if(head2==null) return head1;
 
if(head1.data==head2.data){
IntNode special = difference(head1.next, head2.next);
return special;
}
if(head1.data!=head2.data){
IntNode special = difference(head1.next, head2);
head1.next=special;
 
}
 
if (head1.data < head2.data){
IntNode special =difference(head1, head2.next);
return special;
}
 
return head1;
 
}
 

That was the difference method which will take two list head1, head2

lets say: head1 lis: 3 ; 6 ; 9 ; 10
head2 list is: 5; 6; 10

Answer should be: 3->9, can any one correct me!

Here is another method:

    
public static IntNode mergeUnique(IntNode head1, IntNode head2)
{
 
 
if(head1==null && head2==null) return null;
if(head1==null) return head2;
if(head2==null) return head1;
 
 
if(head1.data==head2.data){
IntNode special = difference(head1.next, head2.next);
return special;
}
if(head1.data!=head2.data){
IntNode special = difference(head1.next, head2);
head1.next=special;
 
}
 
 
if (head1.data < head2.data){
IntNode special=mergeUnique(head1.next, head2);
head1.next=special;
return head1;
}
 
if (head2.data < head1.data){
IntNode special=mergeUnique(head1, head2.next);
head2.next=special;
return head2;
}
 
 
 
 
return head1;
 
}
 

lets say: head1 lis: 3 -> 6 -> 9 -> 10
head2 list is: 5-> 6-> 10

Answer should be: 3,5,6,9,10, can any one correct me!




Note that IntNode class contain:

    
 
public class IntNode
{
public int data;
public IntNode next;
 
public IntNode()
{
data = 0;
next = null;
}
 
public IntNode(int data)
{
this.data = data;
next = null;
}
 
public IntNode(int data, IntNode next)
{
this.data = data;
this.next = next;
}
 

This is how I was trying to test:

  
class test{
 
IntNode head1 = new IntNode(4,
                new IntNode(13,
                new IntNode(23,
new IntNode(27,
new IntNode(34,
new IntNode(42,
new IntNode(48
)))))));
 
IntNode head2 = new IntNode(1,
                new IntNode(8,
                new IntNode(13,
                new IntNode(21,
                new IntNode(42,
                new IntNode(50,
                new IntNode(51
                )))))));
 
IntNode r = MainClass.difference(head1, head2);
                r.print();
 
}

seems like program output partly not what I am expecting result.
[ April 27, 2007: Message edited by: pot tom ]

[fred rosenberger]

It would help if you would use the code tags. When entering your formatted code, hi-lite the code block, then press that "code" button you see below under the "Instant UBB Code". Then, when displayed, it's MUCH easier to read.

Second, what exactly do you mean by "it doesn't run"? Does it error out? does it seem to go into an infinite loop? Does it even compile?

The more details you can give on the exact nature of your problem, the easier it is to help.

[pot tom]

I have modified the code, can anyone please help me.

[Campbell Ritchie]

What is your program doing, what is it supposed to do, and what is the logic behind it?