2. Arrays, Lists, and Dictionaries

2.1 Arrays

Fixed-size, homogeneous data structure.
Indexed using array[i], starting from 1 (in pseudocode) or 0 (in Python).
Use for vote counting, reverse printing, and parallel lists.

Two-Dimensional Arrays:

Access using array[row][col]
Used for tabular data (e.g., sales figures, game scores)

2.2 Lists (Python)

Mutable, ordered collections.
List operations: indexing, slicing, appending, inserting, deleting.

Methods: .append(), .extend(), .insert(), .remove(), .index(), .sort()

Example:

lst = [1, 2, 3]

lst.append(4) # [1, 2, 3, 4]

lst[1] = 10 # [1, 10, 3, 4]

Tuples:

Immutable version of lists: t = (1, 2, 3)

2.3 Dictionaries

Key-value pairs, unordered.
Keys must be immutable types (e.g., strings, numbers).

Methods: .get(), .pop(), .keys(), .values(), .items()

Example:

d = {“a”: 1, “b”: 2}

d[“c”] = 3

d.pop(“b”)