Python

Question 1

What are the logical operators in Python

Answer 1

and, or, and not

Question 2

What are the bitwise operators in Python

Answer 2

&, |, and ^

Question 3

What are the priorities of the sequence operations in Python

Answer 3

x in s, x not in s
s + t, s * n or n * s
s[i], s[i:j], s[i:j:k]
len(s)
min(s)
max(s)
s.index(x[, i[, j]])
s.count(x)

Question 4

What sequence operation is used to test if an item exists in a sequence

Answer 4

x in seq True if x exists in seq, False otherwise
x not in seq False if x exists in seq, True otherwise

Question 5

What sequence operation is used to concatenate two sequences

Answer 5

seq1 + seq2

Question 6

What sequence operation is used to repeat a sequence

Answer 6

seq * n or n*seq

Question 7

What sequence operation is used to return an element or slice of a sequence

Answer 7

seq[i] return the ith element
seq[i:j] slice from i to j, not including j
seq[i:j:k] slice from i to j, not including j, with step k

Question 8

What sequence operation is used to get the length of a sequence

Answer 8

len(seq) the length of seq

Question 9

What sequence operation is used to get the minimum value of a sequence

Answer 9

min(seq) the smallest item of seq

Question 10

What sequence operation is used to get the maximum value of a sequence

Answer 10

max(seq) the largest item of seq

Question 11

What sequence operation is returns the index of an object in a sequence

Answer 11

seq.index(x[,i[, j]]) index of the first occurrence of x (at or after index i and before index j)

Question 12

What sequence operation is counts the number of occurrences of an object in a sequence

Answer 12

seq.count(x) total number of occurrences of x in seq

Question 13

What are the basic sequence types in Python

Answer 13

list, tuple, range

Question 14

What are Falsey values in Python

Answer 14

Constants defined to be false: None and False
Numeric types that are zero: 0, 0.0, 0j, Decimal(0), Fraction(0, 1)
Empty sequences and collections: '', (), [], {}, set(), range(0)

Question 15

What are Truthy values in Python

Answer 15

Constants defined to be true: True
Numeric types that are not zero
Non-empty sequences or collections

Question 16

What data types are valid keys for a hash map/dictionary

Answer 16

Objects: Integer, Float, String, Boolean
Immutable sequences: String, Tuple, Range, Frozenset

Question 17

For small inputs, an array can be faster than a hash map. Why?

Answer 17

There is overhead associated with a hash map such as the hash function

Question 18

When designing a hash map what are some good design choices

Answer 18

1. Use a prime number inf your hash function which helps spread the keys more evenly
2. Design a hash function that spreads hashes evenly to avoid collisions
3. Implement a method to handle collisions: chaining or open addressing

Question 19

How can simulate a stack using a list

Answer 19

stack = []
stack.append(3) # push
stack.pop() # pop
len(stack) # num of element
stack[-1] # peek
if not stack # check empty

Question 20

How can you simulate a queue

Answer 20

# Initialize a queue
from collections import deque
queue = deque()
queue = deque([1,2,3])

queue.append(4) # Enqueue
queue.pop()     # deque
queue[0]        # peek
len(queue)      # get size

Question 21

What built-in function returns the absolute value of a number

Answer 21

abs(x)

>>> abs(-10)
10
>>> abs(-3.145)
3.145

Question 22

What built-in function converts a number to a binary string

Answer 22

bin(x)

>>> bin(10)
'0b1010'
>>> format(10,'b')
'1010'

Question 23

What built-in function returns the string representing a character whose Unicode code point is the integer i

Answer 23

chr(i)

>>> chr(97)
'a'
>>> chr(ord('a'))
'a'

Question 24

What built-in function takes two (non-complex) numbers as arguments and returns a pair of numbers consisting of their quotient and remainder when using integer division

Answer 24

divmod(a, b)

>>> divmod(30,4)
(7, 2)

Question 25

What built-in function returns an enumerate object

Answer 25

enumerate(iterable, start=0)

>>> list(enumerate(['a','b','c']))
[(0, 'a'), (1, 'b'), (2, 'c')]

Question 26

What built-in function returns a floating point number from a number or a string

Answer 26

float(x)

>>> float(1)
1.0
>>> float("   -1.345\n")
-1.345

Question 27

What built-in function returns a new frozenset object

Answer 27

frozenset(iterable=set())

>>> frozenset( [1,2,2,3,4,5,5])
frozenset({1, 2, 3, 4, 5})

Question 28

What built-in function returns the hash value of an object

Answer 28

hash(object)

>>> hash('foo')
9059890961789401645
>>> hash(1)
1
>>> hash(2)
2
>>> hash(True)
1
>>> hash(False)
0
>>> hash((1,2,5))
2143910794424799510

Question 29

What built-in function returns the hexadecimal string of an integer

Answer 29

hex(x)

>>> hex(420)
'0x1a4'
>>> format(420, 'x')
'1a4'
>>> format(420, 'X')
'1A4'

Question 30

What built-in function returns an integer object from a number or a string

Answer 30

int(number=0)
int(string, base=10)

>>> int("1234")
1234
>>> int(123.45)
123
>>> int("1234")
1234
>>> int('   -12_345\n')
-12345
>>> int('0x1a4', 0)
420
>>> int('0b110100100', 0)
420
>>> int('110100100', 2)
420

Question 31

What built-in function returns the length (number of items) in an object

Answer 31

len(s)

Question 32

What built-in function returns a new list object from an iterable

Answer 32

list(iterable)

Question 33

What built-in function returns a map object from a function and multiple iterables

Answer 33

map(function, iterable, *iterables)

If additional iterables arguments are passed, function must take that many arguments and is applied to the items from all iterables in parallel.

Question 34

What built-in function returns the largest item in an iterable or the largest of two or more arguments

Answer 34

max(iterable, *, key=None)
max(iterable, *, default, key=None)
max(arg1, arg2, *args, key=None)

Question 35

What built-in function returns the smallest item in an iterable or the smallest of two or more arguments

Answer 35

min(iterable, *, key=None)
min(iterable, *, default, key=None)
min(arg1, arg2, *args, key=None)

Question 36

What built-in function converts an integer to an octal string

Answer 36

oct(x)

>>> oct(8)
'0o10'
>>> oct(-56)
'-0o70'
>>> format(10, 'o')
'12'

Question 37

What built-in function returns an integer representing a Unicode character

Answer 37

ord(c)

>>> ord('a')
97

Question 38

What built-in function returns the base to the power, e.g. 2^4

Answer 38

pow(base, exp, mod=None)

>>> pow(2,4)
16
>>> 2**4
16

Question 39

What built-in function returns a range object

Answer 39

class range(stop)
class range(start, stop, step=1)

Question 40

What built-in function reverses an sequence

Answer 40

reversed(seq)

seq must implement the \_\_reversed\_\_() method

Question 41

What built-in function returns a new set object from an iterable

Answer 41

set(iterable)

Question 42

What built-in function returns a slice of an object

Answer 42

slice(stop)
slice(start, stop, step=None)

Slice objects are also generated when extend indexing syntax is being used, e.g. a[start:stop:step]

Question 43

What built-in function returns a new sorted list from an iterable

Answer 43

sorted(iterable, /, *, key=None, reverse=False)

Question 44

What built-in function returns a string version of an object

Answer 44

str(object='')
str(object=b'', encoding='utf-8', errors='strict')

Question 45

What built-in function returns sum of an iterable

Answer 45

sum(iterable)
sum(iterable /, start =0)

Question 46

What built-in function returns a new tuple object from an iterable

Answer 46

tuple(iterable)

Question 47

What built-in function is used to iterate over several iterables in parallel

Answer 47

zip(*iterables, strict=False)

>>> for item in zip([1,2,3], ['a','b','c']):
...     print(item)
... 
(1, 'a')
(2, 'b')
(3, 'c')