Problem 3.5: Bigger Path (100 pts)

Now, implement bigger_path, which removes the restriction that paths must begin at the root -- they can begin at any node. You can use bigpath to help your implementation.

def bigger_path(t, n):
    """Return the number of paths in t that have a sum larger or equal to n.

    >>> t = tree(1, [tree(2), tree(3, [tree(4), tree(5)])])
    >>> bigger_path(t, 3)
    9
    >>> bigger_path(t, 6)
    4
    >>> bigger_path(t, 9)
    1
    """
    "*** YOUR CODE HERE ***"