Bring out a white paper and write all the answers to the quiz on the paper. See if you can finish all of these answers.

1. How do you create a array which contains 2 - 10 in one-liner?

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   # using list comprehension
   [i for i in range(2, 11)]
   # Or
   list(range(2, 11))
   

2. How do you randomly select 3 numbers from an integer array “‘A”’?

   import random
   random.sample(A, 3)
   

3. How do you create a array of length 13 that for index > 4 its element is any random lowercase vowel(‘a’, ‘e’, ‘i’, ‘o’, ‘u’) but for index in [0, 4], its element is the square root value of the index?

   import random
   # random.sample's return type is a list
   [i**0.5 if i < 5 else random.sample('aeiou', 1)[0] for i in range(13)]
   

4. How do you you heap sort an array A? How do you add a new value into a heap? How do you pop the root value from a heap? How do you add a new number to a min heap with a fixed length?

   import heapq
   heapq.heapify(A)
   heapq.heappush(A, a)
   b = heapq.heappop(A)
   b = heapq.heappushpop(A, a)
   

5. How do you find all the permutations of a string s?

   import itertools
   itertools.permutations(s)
   

6. How do you combine two same-length arrays A and B as a pair array?

   zip(A, B)
   # if A and B is not same length, what's the result?
   

7. Given a key “WTF” and a dictionary d, how do you find the value of the key and if the key doesn’t exist in the dict, can you return “” instead?(one-liner)

   d.get("WTF", "")
   

8. How do you replace all the “is” to “si” in string “isawakiss”?

   "isawakiss".replace("is", "si")
   

9. How do you replace all the vowels in a string to '_'?(regex)

   import re
   re.sub("[aeiou]", "_", s)
   

10. lowercase and uppercase of the string s?

    s.lower()
    s.upper()
    # print the alphabet
    import string
    string.ascii_letters
    string.ascii_lowercase
    

11. convert all the elements in string array S into the form specified in question 9, and combine the result string array into one huge string?

    ''.join([re.sub('[aeiou]', '_', s) for s in S])
    

12. how do you convert base-2 binary number string to int?

    int("10001", 2)
    

13. how do you find the binary expression of a 10-base number?

    bin(23)[2:]
    

14. Do you know how to do string formatting in python? For example, given a list A, can you print something like “hey, look. This is a list: ####?” “####” represents the contents in the list.

    "hey, look. This is a list: %s" % A
    "hey, look. This is a number: %d" % 23
    "hey, look. This is a string: %s" % "WTF"
    "hey, look. This is a float number: %f " % 3.14
    

15. What is the output of the following program?

    names = "{1}, {2} and {0}".format('John', 'Bill', 'Sean')
    print(names)
    

    Bill, Sean and John
    

16. How to print the clock time in this format “XX:XX:XX” given the total seconds s? (one-liner)

    "{:02d}:{:02d}:{:02d}".format(secs // 3600, *divmod(secs % 3600, 60))
    # print the clock time
    import time
    time.strttime('%H : %M : %S')
    time.strttime('%I : %M : %S %p')
    

17. What is the built-in functions to convert between ASCII numbers and characters?

    ord('s')
    chr(65)
    
    

18. How do you determine if a character is a digit or not, is a letter or not?

    's'.isdigit()
    's'.isalpha()