Introduction to Computer Science: The Way of the Program — Homework 13

Due by 11:59pm Tuesday, December 12

Reading

Programming Exercises

  1. Finish all of your recursive function definitions from Lab 13.

EXTRA CREDIT PROBLEMS (OPTIONAL)

  1. Write a recursive function ruler(n) that prints out a "vertical ruler" pattern of dashes, where n is an integer > 0. The middle row of the pattern should be a row of n dashes, with a row of n-1 dashes in the middle of the top and bottom halves of the ruler. The ruler should continue to be subdivided until the smallest section is labeled by a single dash. Some examples are shown below:

    >>> ruler(1)
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>>> ruler(2)
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--
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>>> ruler(3)
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--
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---
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--
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>>> ruler(4)
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--
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---
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--
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----
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--
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---
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  2. In blackjack, the face cards Jack, Queen, and King are worth 10 points each, and an Ace can be worth either 1 or 11, depending on circumstances. The other non-face cards are each worth their rank (2 through 10). Write a program called worth(cards) that takes as input a list of cards representing a hand, and returns a list of all possible values for the hand, with Aces counted as either 1 or 11. Each card is represented either as a string "Jack", "Queen", "King", "Ace", or as a number from 2 to 10. The list of values returned should not contain duplicates, and the order of the values does not matter. Some examples are shown below. Notice that 0 is the only possible value for an empty hand. Hint: use a recursive approach similar to the programs subsets and binaryStrings.

    >>> worth([8, "King"])
[18]
>>> worth(["Jack", "Ace"])
[11, 21]
>>> worth(["Ace", "Ace", "Ace"])
[3, 13, 23, 33]
>>> worth(["Ace", "King", 5, 2, "Ace", "Ace"])
[20, 30, 40, 50]
>>> worth([])
[0]

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