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1. What does this program print? ``

python
count = [0] * 26
s = "mississippi"
for ch in s:
    count[ord(ch) - ord("a")] += 1
print(count[ord("s") - ord("a")] + count[ord("p") - ord("a")])

``

6425

2. What does this program print? ``

python
class StampSeen:
    def __init__(self, size):
        self.stamp = [0] * size
        self.current = 1

    def reset(self):
        self.current += 1

    def seen_before(self, v):
        if self.stamp[v] == self.current:
            return True
        self.stamp[v] = self.current
        return False

st = StampSeen(10)
results = [st.seen_before(4), st.seen_before(4)]
st.reset()
results.append(st.seen_before(4))
results.append(st.seen_before(7))
print(results)

``

[False, True, True, False][True, True, False, False][False, False, False, False][False, True, False, False]

3. In the StampSeen class, why does current start at 1 instead of 0?

Python cannot store a 0 in an int attributeEvery slot of a new list holds 0, so with current at 0 every value would look already seenStarting at 0 makes the first reset raise an errorThe first call to seen_before must always return True

4. A program must track which of five ids it has seen. The ids are whole numbers up to 2,000,000,000. Which choice fits best?

A list of booleans with 2,000,000,001 slots, because index lookups are always cheaperA list of length 5, because there are five idsA set, because it stores only the five values that were addedA list of length 2,000,000,000 filled with zeros

5. When you write [False] * 101, what value does every slot start with? Type one word.

Type your answer.

Counting and seen arrays