change the info part of each node in binary tree
In my point of view, since you want to use the next info in the inorder traversal, you have to do a function that traverse you tree backward for this order.

    int change(node* n,int next){
     int k;
     k=next;
     if(n){
      if(n-&gt;right) k = change(n-&gt;right,next);
      if(n-&gt;left) change(n-&gt;left,n-&gt;info);
      n-&gt;info += k;
     }
    }


That way, calling

     change(root,0)


You have next that is the info of the next node in your order.

I hope I didn't made a mistake and that it help.