push_swap — Sorting Algorithm in C

42 Urduliz — Common Core project

Sorts a stack of integers using the minimum number of operations with only two stacks (a and b) and a limited set of instructions.

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Operations

Op	Description
sa / sb	Swap top two elements of stack a/b
pa / pb	Push top of b to a / top of a to b
ra / rb	Rotate stack a/b upward
rra / rrb	Reverse rotate stack a/b
ss / rr / rrr	Combined operations

Build & Run

make
./push_swap 5 2 8 1 3

Check with the included tester:

python3 tester.py

Algorithm

Uses a quicksort-based approach with optimization for small sets (≤5 elements handled with hardcoded optimal paths). For larger sets, recursively partitions using a pivot and moves chunks between stacks.

Performance targets:

• 3 numbers: ≤ 3 ops
• 5 numbers: ≤ 12 ops
• 100 numbers: ≤ 700 ops
• 500 numbers: ≤ 5500 ops

Project Structure

push_swap/
├── algorithm/       # Quicksort and final sort logic
├── actions/         # push, swap, rotate, reverse_rotate
├── core/            # Argument validation, stack creation
├── utils/           # Free, atoi, helpers
├── printf/          # Embedded ft_printf
├── push_swap.h
└── Makefile

Skills

C Algorithms Data Structures Stack Sorting Optimization

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Academic Integrity

This repository is shared for educational and portfolio purposes only.

For 42 students:

• Do not copy this code for your own project submissions
• Use it as a reference to understand concepts and approaches
• Write your own original solution — that is the only way to actually learn

42's core values are learning through practice, peer collaboration, and genuine problem-solving.

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License

MIT — see LICENSE for details. Copyright (c) 2026 Eneko Muñoz Bordona