Exam Rank 03 — 42 School: Exercise Solutions

This repository contains solutions to the Exam Rank 03 exercises from the 42 School curriculum. The content is organized by exercise level and includes the exercise subjects (for reference) together with example implementations and build scripts where applicable.

This README provides an overview of the repository, how to build and run the exercises, a short description of each exercise, and testing notes.

Repository layout

• level-1/

  • broken_gnl/ — a variant of the "get_next_line" assignment (broken/intentional-bug version and subject)
  • filter/ — program that replaces occurrences of a substring with asterisks
  • scanf/ — partial implementation of ft_scanf

• level-2/

  • n_queens/ — N-Queens solutions with Makefile and subject
  • permutations/ — generate all permutations of a string in alphabetical order
  • powerset/ — find subsets that sum to a target value
  • tsp/ — brute-force traveling salesman solver (small n)
  • rip/ — parentheses balancing and minimal removal solutions

Each exercise directory typically contains:

• subject.txt or README.md — the exercise statement provided for reference
• *.c, *.h — implementation and headers
• Makefile — build helper (for many level-2 exercises)

Purpose and license

The exercise subjects are the property of 42 School and are included for educational reference. Implementations contained in this repository are the original work of the repository author and are provided for non-commercial educational use only (see LICENSE for full terms and contact information).

Building

General notes:

• The projects are standard C programs and use gcc.
• Several level-2 directories include a Makefile with standard targets:
  • make / make all — compile the program
  • make clean — remove object files
  • make fclean — remove object files and executable
  • make re — rebuild from scratch
  • make test — run example tests (where provided)

Examples (run from repository root):

Change into an exercise directory and build:

cd level-2/n_queens
make

For tsp the Makefile links against libm, so the -lm flag is used automatically.

Running the exercises (summary)

Below are concise descriptions and usage examples for each exercise. For full details refer to the exercise subject.txt or the directory README.

• broken_gnl (level-1/broken_gnl)

  • Purpose: an implementation of a get_next_line-like function. The directory includes a subject and a sample (intentionally flawed) solution.

• filter (level-1/filter)

  • Purpose: read stdin and replace every occurrence of the given pattern with a sequence of asterisks of equal length.
  • Usage: ./filter <pattern>
  • Example: echo "abcabc" | ./filter abc outputs *** *** (without spaces)

• scanf (level-1/scanf)

  • Purpose: partial reimplementation of scanf supporting %s, %d and %c.
  • The directory contains a working ft_scanf.c and helper subject file.

• n_queens (level-2/n_queens)

  • Purpose: print all valid placements of N queens on an N×N board.
  • Usage: ./n_queens N
  • Output: lines with N integers representing row positions for each column.

• permutations (level-2/permutations)

  • Purpose: print all permutations of the input string in alphabetical order.
  • Usage: ./permutations <string>

• powerset (level-2/powerset)

  • Purpose: list all subsets of the provided set whose elements sum to the target integer (first argument).
  • Usage: ./powerset <target> <list of distinct integers>

• tsp (level-2/tsp)

  • Purpose: brute-force shortest closed path visiting all given points (n ≤ 11).
  • Usage: ./tsp < input.txt where input has lines like x, y (floating points).
  • Output: a single floating number formatted to two decimals (e.g. 8.00).

• rip (level-2/rip)

  • Purpose: remove the minimum number of parentheses (replace by spaces) to make input strings balanced and print all distinct minimal solutions.
  • Usage: ./rip "( )..."

Testing notes

• Many directories include example Makefile targets named test that run the compiled binary with sample inputs from the exercise statements. Use those targets to verify behavior quickly.
• For exercises that read from stdin, you can pipe data via echo or use file redirection: ./tsp < level-2/tsp/square.txt.

Quality and limitations

• These are educational implementations. Some directories include intentionally broken code (for debugging practice) or partial templates intended to be completed.
• The programs follow the constraints given in each subject (allowed functions, expected behavior on edge cases, and error handling).

Contributing and contact

This repository is a personal collection of exercise solutions. Contributions are welcome as long as they follow the repository license and respect the original exercise authorship. For questions, corrections or requests regarding licensing or removal of subject material, contact the repository owner (see LICENSE).

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Last updated: October 2025