Python Tricks

array = [1, 1, 1, 3]

array.count(1) # 3
array.find(1) # 0 
array.rfind(1) # 2
array.find(2) # -1

Dict

d ={}
d.get('cat', 0) # 0 - setting default if key doesn't exist

from collections import defaultdict

d = defaultdict(int) # (dict, but if key doesn't exist then create one with some default value)
d['cat'] # 0

Set

Tuple

float('inf')
float('-inf')

import math

math.ceil(2.2) # 3
math.floor(2.8) # 2

defaultdict (dict, but if key doesn't exist then create one with some default value)
dequeu (push and pop from both ends with O(1))
Counter (makes counter dict of the iterrable)

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