Week 4: Exercises

1. Hands of Cards

Consider this class:

enum Suit { Clubs, Diamonds, Hearts, Spades };

class Card {
    public int rank;    // 1 = Ace, 2 .. 10, 11 = Jack, 12 = Queen, 13 = King 
    public Suit suit;

    public Card(int rank, Suit suit) {
        this.rank = rank;
        this.suit = suit;
    }

}

a) Add a method string describe() that returns a string description such as "7 of Diamonds" or "Jack of Hearts".

b) Write a class Deck with these members:

• Deck() - return a new deck of 52 cards

• Card[] deal(int n) – return an array of n cards randomly chosen from the remaining cards in the Deck, and remove them from the deck. If fewer than n cards remain, return null.

• int count() - return the number of cards currently remaining in the deck

2. Polynomials

Design and implement a C# class Polynomial representing a polynomial of a single variable. Your class should include the following:

• a constructor that takes a variable number of arguments of type double, yielding a polynomial with those coefficients. For example,

      new Polynomial(1.0, 4.0, 5.0)

  should yield the polynomial x² + 4x + 5.

• a property degree that returns the degree of a polynomial. For example, the polynomial above has degree 2.

• an overloaded operator + that adds two polynomials

• an overloaded operator - that subtracts two polynomials

• an overloaded operator * that multiplies two polynomials, or a polynomial and a scalar

• a method that evaluates a polynomial for a given value of x

• a method that returns the first derivative of a polynomial

• a ToString() method that yields a string such as "x^2 + 4x + 5"

• a static method Parse() that parses a string such as "x^2 + 4x + 5", yielding a polynomial.

3. Double-Ended Queue

Write a class Deque implementing a double-ended queue of integers:

Your class should have these members:

• Deque()

• bool isEmpty()

• void enqueueFirst(int i)

• int dequeueFirst()

• void enqueueLast(int i)

• int dequeueLast()

All operations should run in O(1). In dequeueFirst() and dequeueLast(), you may assume that the queue is not empty.

4. Dictionary

Write a class SIDict that represents a dictionary from strings to integers. It should have the following members:

• SIDict() - create an empty SIDict

• an indexer that allows the user to get or set values by index

For example, your class could be used as follows:

SIDict d = new SIDict()
d["red"] = 4
d["blue"] = 5
d["red"] += 1
WriteLine(d["red"])

Use a linked list of key-value pairs.