Python syntax for arrays and strings

nums[i]

Accesses the element at index i

nums[-1]

Accesses the last element

nums[a:b]

Gets elements from index a to b - 1

nums[::-1]

Returns nums reversed

nums.append(x)

Adds x to the end of nums

nums.pop()

Removes and returns the last element

nums.sort()

Sorts nums in place ascending

sorted(nums)

Returns a new sorted list

[x for x in nums if x > 0]

Creates a list of positive values

s[i]

Accesses character at index i

s[a:b]

Gets substring from index a to b - 1

s.split()

Splits string by whitespace

"".join(chars)

Joins characters into one string

ord(c) - ord("a")

Maps some lower case letter c to index 0 through 25 by taking advantage of ascii values of lowercase letters

[[0] * cols for _ in range(rows)]

Creates a 2D grid with independent rows