Code Golf Cheatsheet

# STRINGS
s[::-1]                 # reverse string
s*3                     # repeat string
s.count("a")            # count substring
"a"in s                 # membership test
min(s),max(s)           # lexicographic min/max char
s.split()               # split on whitespace
",".join(a)             # join iterable into string
"".join(map(str,a))     # join numbers
s.lower(),s.upper()     # case transform
s.swapcase()            # swap lower/upper
s.isalpha()             # letters only
s.isalnum()             # letters + digits
s.isdigit()             # digits only

# CONVERSIONS
int(s)                  # string → int
int(s,b)                # base-b → int
bin(n)[2:]              # int → binary
hex(n)[2:]              # int → hex
oct(n)[2:]              # int → octal
chr(n)                  # int → char
ord(c)                  # char → int
str(n)                  # anything → string

# FORMAT STRINGS
f"{x:.2f}"              # float with 2 decimals
f"{x:.0f}"              # rounded float
f"{n:03}"               # zero-pad integer
f"{n:b}"                # binary format
f"{n:x}"                # hex format
"%.2f"%x                # short float formatting
"%d"%x                  # integer formatting

# ITERABLES
[*map(f,a)]             # map without list()
[*filter(f,a)]          # filter without list()
[x for x in a]          # comprehension
[x for x in a if c]     # filtered comprehension
sum(a)                  # sum elements
len(a)                  # length
sorted(a)               # sort iterable
sorted(numbers, key=lambda n: sum(map(int, str(n)))) # example of key parameter: sort numbers by the sum of their digits
a[::-1]                 # reverse list
max(a),min(a)           # extrema
list(set(a))            # remove duplicates
"".join(a)              # join chars

# MATH/LOGIC/BITS
x>>1                    # divide by 2 (positive ints)
x<<1                    # multiply by 2
x&1                     # parity (odd/even)
x^y                     # xor
x**.5                   # square root
round(x,1)              # round to 1 decimal
abs(x)                  # absolute value
divmod(a,b)             # quotient and remainder
x<y<z                   # chained comparison
a and b                 # logical AND
a or b                  # logical OR

# LAMBDAS/EXPRESSIONS
lambda x:x*x            # anonymous function
(lambda x:x*x)(n)       # inline lambda call
a if c else b           # ternary expression

# DICTS/SETS
d.get(k,0)              # safe dict access
{k:v for k,v in a}      # dict comprehension
set(a)                  # unique elements
len(set(a))             # count uniques

# INPUT/OUTPUT
I=input			# when more than one input(), use I() for shorter code
int(input())            # read int
map(int,input().split())# read ints
print(*a)               # space-separated output

# USEFUL ONE LINERS
sum(map(int,input().split()))      # sum input numbers
print(*sorted(map(int,input().split()))) # sort input
print("YES"if c else"NO")          # conditional output
all(a)                             # all True
any(a)                             # any True
["even","odd"][d%2]      # will return "even" if d%2 equals 0 or "odd" if it equals 1