Lists and Sequences (Python)

This module practices storing sequences, iterating them, and computing frequencies.

Learning Metadata

• Difficulty: Beginner.
• Estimated Time: 20-35 minutes.
• Prerequisites: 01-foundations/control-flow, 01-foundations/functions.
• Cross-Language Lens: Compare vector, List<T>, slices, and Python lists as different tradeoffs for dynamic sequence handling.

Learning Outcomes

• FND-SEQ-01: Store and traverse ordered collections safely.
• FND-SEQ-02: Handle empty collections and index boundaries explicitly.

Quick Run

Run from the repository root:

python scripts/automation.py run-module --module-path languages/python/01-foundations/arrays-and-vectors

Topics Covered

• Building dynamic collections from user input.
• Forward and reverse iteration patterns.
• Counting occurrences of a target value.
• Handling empty or invalid-size collections.

Common Pitfalls

• Trusting collection size input when count is zero or negative.
• Off-by-one errors while reading N elements.
• Not handling empty input in frequency tasks.

Cross-Language Notes

• In Python, read this module through the native focus ?Lists and Sequences?; the shared folder name remains stable for side-by-side navigation.
• Use dynamic values, collection protocols, and context managers to demonstrate how to store and traverse ordered collections safely.
• Compare observable behavior with the other tracks when learning to handle empty collections and index boundaries explicitly; equivalent evidence matters more than identical syntax.

Exercise Focus

• exercises/01.py: read N integers, store them, and print them in reverse order.
• exercises/02.py: read a collection and count frequency for a target integer.

Exercise Specs

1. exercises/01.py

• Input: positive integer count and then count integers.
• Output: values printed in reverse insertion order.
• Edge cases: count <= 0; repeated values in the collection.

2. exercises/02.py

• Input: integer list plus a target integer.
• Output: frequency count for target value.
• Edge cases: empty list input; target not present.

Check Your Work

Run from the repository root after implementing a starter:

python scripts/automation.py check-exercise --language python --level 01-foundations --module arrays-and-vectors --exercise 01

Change --exercise 01 to --exercise 02 for the second task. Consult exercises/solutions/ only after making a complete attempt.

Checkpoint

• I can explain the core ideas of this module.
• I can run and modify example/main.py.
• I completed exercises/01.py.
• I completed exercises/02.py.
• I validated at least one edge case for each exercise.

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