pingpong.py

# Q3.

"1 2 3 4 5 6 [7] 6 5 4 3 2 1 [0] 1 2 [3] 2 1 0 [-1] 0 1 2 3 4 [5] [4] 5 6"


def pingpong(n):
    """Return the nth element of the ping-pong sequence.

    >>> pingpong(7)
    7
    >>> pingpong(8)
    6
    >>> pingpong(15)
    1
    >>> pingpong(21)
    -1
    >>> pingpong(22)
    0
    >>> pingpong(30)
    6
    >>> pingpong(68)
    2
    >>> pingpong(69)
    1
    >>> pingpong(70)
    0
    >>> pingpong(71)
    1
    >>> pingpong(72)
    0
    >>> pingpong(100)
    2
    """
    "*** YOUR CODE HERE ***"

    def goDirection(value, end, order, nth):
        if nth == end:
            return value

        else:
            if (nth + 1) % 7 == 0 or (value + order) % 7 == 0:
                return goDirection(value + order, end, -order, nth + 1)

            else:
                return goDirection(value + order, end, order, nth + 1)

    return goDirection(0, n, 1, 0)