Binary tree recursive problem

Question

I found this problem and I am not very sure if my approach approach is right:

"A binary tree can be encoded using two functions l and r such that for a node n, l(n) gives the left child of n(or nil if there is none) and r(n) gives the right child(or nil if there is none).Let Test(l,r,x) be a simple recursive algorithm for taking a binary tree encoded by the l and r functions together with the root node x for the binary tree, and returns "yes" if no node in the tree has exactly one child. Give the pseudocode for this algorithm."

I tried this:

test(l,r,x)
  if((l(x)!=null && r(x)!=null) || (l(x)==null && r(x)==null)) 
     return "yes"
   else return "no"

  if(test(l,r,l(x))=="yes") test (l,r,l(x)) else return "no"
  if(test(l,r,r(x))=="yes") test (l,r,r(x)) else return "no"

 return "yes"

Is it correct? If l and r are functions, why are they passed as normal parameters when the function is called?

Thank you in advance for your answers!

Answer 1

the first thing you do is either return yes or no, so the last part is unreachable.

I would change it so that if you have one child, you return no, otherwise you return yes or no depending on if your children meet the criteria.

test(l,r,x)
  if((l(x)!=null && r(x)==null) || (l(x)==null && r(x)!=null)) 
     return "no"
  if(l(x) == null && r(x) == null) 
    return "yes"
  return test(l,r,l(x)) && test(l,r,r(x))