MyTest2Q1Answer

# Begin exam Code by Prof. Danny Heap
class BTNode:
    """Node in a binary tree"""

    def __init__(self: 'BTNode', value: object, left: 'BTNode',
                 right: 'BTNode') -> None:
        """
        Create a new BTNode with value and (possibly)
        children left and right.
        """
        self.value, self.left, self.right = value, left, right


def count_nodes(n: BTNode) -> (int, int):
    """
    Return a tuple containing the number of interior nodes and the number
    of leaves in the tree rooted at n, or (0,0) if n is None.


    <Test cases go here>
    """
    # Begin student code
    if not n: return 0, 0 # this is a line of code[added when checking answers]
    if not n.left and not n.right:
        return 0, 1
    else:
        left_count = (0, 0)
        right_count = (0, 0)

        if n.left:
            left_count = count_nodes(n.left)
            left_count[0] += 1

        if n.right:
            right_count = count_nodes(n.right)
            right_count[0] += 1

        return left_count[0] + right_count[0], left_count[1] + right_count[1]