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1. What does this program print? ``

python
print('Ada,,London,'.split(','))
print(len('Ada,,London,'.split(',')))

``

['Ada', 'London'] 2['Ada', '', 'London', ''] 4['Ada', '', 'London'] 3['Ada', ',', 'London', ','] 4

2. What does 'a b c '.split() return? The text has two spaces after the a and one space at the end.

['a', '', 'b', 'c', '']['a', 'b', 'c']['a b c ']['a', 'b', 'c', '']

3. What does this program print? ``

python
import csv

row = next(csv.reader(['"Smith, John",42,Leeds']))
print(len(row))
print(row[0])

``

4 "Smith3 "Smith, John"2 Smith, John3 Smith, John

4. Which expression is the worst-case number of character comparisons for naive substring search, when the text has n characters and the pattern has m characters?

(n - m + 1) * mn + mn * nm - n

5. What does this program print? ``

python
comparisons = 0

def naive_search(text, pattern):
    global comparisons
    n = len(text)
    m = len(pattern)
    for start in range(n - m + 1):
        j = 0
        while j < m:
            comparisons += 1
            if text[start + j] != pattern[j]:
                break
            j += 1
        if j == m:
            return start
    return -1

at = naive_search('aaab', 'aab')
print(f'found at {at} after {comparisons} comparisons')

``

found at 0 after 3 comparisonsfound at 1 after 4 comparisonsfound at 1 after 6 comparisonsfound at 1 after 3 comparisons

CSV and search