Exercise

1. In CoffeeDB.java, we maintain a collection of coffees in an ArrayList, and this class offers a simple search method:

public List<Coffee> findByName(String name) {
    ...
}

Your task is to complete its Python version below in coffee_db.py:

def find_by_name(self, name):
    pass

2. HashMap and dict.

• What would you get if the key does not exist for HashMap in Java?
• What is the difference between indexing syntax and get() to obtain a value for dict in Python?

3. Please add a method to delete books by the names from a shop cart in ShopCart.java or shop_cart.py. (Hint: it does not make sense to store an item when its amount is less or equal 0.)

4. Please write unit tests for naive_two_sum.py. (Hint: you can refer to the Java implementation NaiveTwoSumTest.java.)

5. Please give a big O characterization in terms of n for each function shown in example.py.

6. Perform experimental analysis to test the hypothesis that Java's sort() or Python's sorted() method runs in \(O(n\log{n})\) on average.

// a is a random list
List<Integer> a = Arrays.asList(1, 9, 4, 6);
Collections.sort(a);

# a is a random list
a = [1, 9, 6, 4]
a = sorted(a)

7. Please give a big O characterization in terms of n for BinarySearch.java or binary_search.py.

8. Please design experiments to compare the efficiency between fast_two_sum.py and naive_two_sum.py.