Python basics
20+ helpful Python syntax patterns for coding interviews
Integers
Integers in python3 are unbounded
Examples
- Happy Number
Power
x = -2
print(x**2) # 4
print(x*x) # 4
Square root *
import math
math.sqrt(49)
# 7
Modulus(%) vs Floor(//)
Modulus: The modulus-function computes the remainder of a division, which is the "leftover" of an integral division.
Floor: The floor-function provides the lower-bound of an integral division. The upper-bound is computed by the ceil function. (Basically speaking, the floor-function cuts off all decimals).
# modulus
print(324 % 10) # 4
# floor
print(324 // 10) # 32
math.ceil() & math.floor()
import math
math.ceil(2.17) # 3
math.floor(2.17) # 2
Infinity (can be used for math.max)
float("inf")
float("-inf")
.isalpha() .isnumeric() & .isalnum()
chr() & ord()
Other
Lambda functions
>>> (lambda x, y: x + y)(2, 3)
5
>>> double = lambda x: x * 2
>>> double(4)
Example usage
# Program to double each item in a list using map()
my_list = [1, 5, 4, 6, 8, 11, 3, 12]
new_list = list(map(lambda x: x * 2 , my_list))
print(new_list) # [2, 10, 8, 12, 16, 22, 6, 24]
Sort
Random
random.random()
Return the next random floating point number in the range [0.0, 1.0]
import random
>>> random.random()
0.6280590213451548
>>> random.random()
0.1623939995862359
>>> random.random()
0.6704949828925247
>>> random.random()
0.6838627536588555
random.randrange(start,stop,step)
Return a randomly selected element from range(start, stop, step). This is equivalent to choice(range(start, stop, step)), but doesn’t actually build a range object.
import random
>>> random.randrange(20)
7
>>> random.randrange(10,20,2)
16
>>> random.randrange(start=10,stop=20,step=2)
18
>>> random.randrange(start=10,stop=20,step=2)
14
>>> random.randrange(start=10,stop=20,step=2)
12
>>> random.randrange(start=10,stop=20,step=2)
14
>>> random.randrange(start=10,stop=20,step=2)
16
>>> random.randrange(start=10,stop=20,step=2)
18
>>> random.randrange(start=10,stop=20,step=2)
18
>>> random.randrange(start=10,stop=20,step=2)
18
>>> random.randrange(start=10,stop=20,step=2)
16
>>> random.randrange(start=10,stop=20,step=2)
16
>>> random.randrange(start=10,stop=20,step=2)
random.randint(a,b)
Return a random integer N such that a <= N <= b. Alias for randrange(a, b+1)
import random
>>> random.randint(10,20)
19
>>> random.randint(10,20)
16
>>> random.randint(10,20)
15
>>> random.randint(10,20)
20
>>> random.randint(10,20)
11
>>> random.randint(10,20)
17
>>> random.randint(10,20)
20
>>> random.randint(10,20)
random.choice(seq)
Return a random element from the non-empty sequence seq
import random
>>> random.choice(['win', 'lose', 'draw'])
'lose'
>>> random.choice(['win', 'lose', 'draw'])
'win'
>>> random.choice(['win', 'lose', 'draw'])
'win'
>>> random.choice(['win', 'lose', 'draw'])
'win'
>>> random.choice(['win', 'lose', 'draw'])
'lose'
>>> random.choice(['win', 'lose', 'draw'])
'lose'
>>> random.choice(['win', 'lose', 'draw'])
'draw'
heapq
collections
collections.deque() *
collections.defaultdict
collections.OrderedDict
sortedcontainers.SortedDict
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Created: December 13, 2021 16:05:48