interview_cheatsheet.md

Interview intermediate cheat sheet

Use enumerate() to iterate over both indices and values instead of range()

numbers = [45, 22, 14, 65, 97, 72]
for i, num in enumerate(numbers, start=52):
    print(i, num)
52 45
53 22
54 14
55 65
56 97
57 72

Use list comprehension instead of map() and filter()

[(lambda x: x * x )(x) for x in [1, 2, -5, 4]]
[1, 4, 25, 16]

Use breakpoint() instead of print()

you need to import pdb explicitlly for python < 3 import pdb; pdb.set_trace()

Use f from string module to print strings

def get_name_and_decades(name, age):
    return f"My name is {name} and I'm {age / 10:.5f} decades old."
get_name_and_decades("Maria", 31)
My name is Maria and I'm 3.10000 decades old.

Use sorted() to sort complex lists

sorted(['cat', 'dog', 'cheetah', 'rhino', 'bear'], reverse=True)
['rhino', 'dog', 'cheetah', 'cat', 'bear]

or in dictionary

sorted(animals, key=lambda animal: animal['age'])
[
    {'type': 'elephant', 'name': 'Devon', 'age': 3},
    {'type': 'puma', 'name': 'Moe', 'age': 5},
    {'type': 'penguin', 'name': 'Stephanie, 'age': 8},
]

Store unique values in a set() , O(1) time complexity

def get_unique_words():
...     words = set()
...     for _ in range(1000):
...         words.add(get_random_word())
...     return words
>>> get_unique_words()
{'world', 'all', 'the', 'words'}

Save memory with generators

sum((i * i for i in range(1, 1001)))
333833500

Define Default Values in Dictionaries With .get() and .setdefault()

MIT