Counting nodes in a tree in Java

Question

First of all, I swear this is not homework, it\'s a question I was asked in an interview. I think I made a mess of it (though I did realise the solution requires recursion).

Answer 1

Questions related to binary tree should be expected in an interview. I would say to take time before any next interview and go through this link. There are about 14 problems solved .You can have a look and how the solution is done. This would give you an idea of how to tackle a problem with binary tree in future.

I know your question is specific to the count method .That is also implemented in the link that i provided

Answer 2

return (getRightChild() == null ? 0 : getRightChild.count()) + (getLeftChild() == null ? 0 : getLeftChild.count()) + 1;

Or something like that.

Answer 3

class Tree {

  Tree getRightChild() {
    // Assume this is already implemented
  }

  Tree getLeftChild() {
    // Assume this is already implemented
  }

  int count() {
   return 1 
      + getRightChild() == null? 0 : getRightChild().count()
      + getLeftChild() == null? 0 : getLeftChild().count();
  }
}