how to deside the order of the parts..

I got this solution to the tree2list function.

The 3rd part of this solution is going to the tail of the linked list.
The 4th part is the linking part.

I think its odd to go threw the list and then do the linking.

I think we need to do the linking first (in order to have a list) and then go to the last member of the list.

Code:

---

node* tree2list(node*root) {
 node *head,*temp;

if (!root) return NULL;
head=tree2list(root->left);
if (!head) return root;

for(temp=head;temp->next;temp=temp->next){  //3rd part
}

temp->next=root;                                          //4th part
root->next=tree2list(root->right);

return head;

}

---

Is this a solution you have come up with yourself? You have a recursive search through the left branch of this tree, but how are you really going down the right side? Your Recursive function tree2list is exclusive for the left side branch unless I have overlooked something.

Seems that some of this solution is missing. What is the intent of your for loop and and empty block for your third part?

my recursion is fine

you can do a trace on a simple binary tree

Your recursion doesn't look fine to me....