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1. Which statement about a hash collision is correct?

It is an error that stops a dict from runningIt happens when two different keys land in the same bucket, and the dict then uses == to tell them apartIt happens only when two keys are equalIt means the table has more buckets than entries

2. A dict picks a bucket from the hash of a key. A table has 16 buckets, and hash(35) is 35 because Python ints hash to themselves. Which bucket does 35 go to, using hash(35) % 16?

1135319

3. What does this program print? ``

python
d = {}
d[-1] = 'a'
d[-2] = 'b'
print(len(d))
print(d[-1], d[-2])
print(d.get(-3))

``

1, then a b, then None2, then b a, then None2, then a b, then 02, then a b, then None

4. What does this program print? ``

python
class Tag:
    def __init__(self, name, hash_value):
        self.name = name
        self.hash_value = hash_value

    def __hash__(self):
        return self.hash_value

    def __eq__(self, other):
        if self is other:
            return True
        if not isinstance(other, Tag):
            return False
        return self.name == other.name

s = set()
s.add(Tag('a', 7))
s.add(Tag('b', 7))
s.add(Tag('a', 7))
print(len(s))
print(Tag('b', 7) in s)
print(Tag('c', 7) in s)

``

3, then True, then False2, then True, then False2, then False, then False2, then True, then True

5. This class is used as a dict key or set item. What happens when the program runs Name('Ana') == 'Ana'? ``

python
class Name:
    def __init__(self, first):
        self.first = first

    def __eq__(self, other):
        return self.first == other.first

``

It raises AttributeError, because a str has no attribute named first, and __eq__ does not check the type of otherIt prints False, because a str is never a NameIt prints True, because both names are 'Ana'It raises TypeError, because == compares only numbers

Hashing with dict and set