Quick Sort

# Quick Sort

Zerethon Official Sample `quick-sort`, version 1.2.0, Python 3.12.

- `quick_sort.py` — the algorithm, as shown in Zerethon Tools
- `main.py` — entry file: a short demonstration
- `test_quick_sort.py` — checks; set it as the entry file to run them

This project is your own copy. Changing it never changes the official sample.
See the algorithm animated: https://tools.zerethon.com/quick-sort-visualizer

from quick_sort import quick_sort

numbers = [38, 27, 43, 3, 9, 82, 10, 27]
print("Before:", numbers)
result = quick_sort(list(numbers))
print("After: ", result)
print("Same as sorted():", result == sorted(numbers))

"""Quick Sort (Zerethon Official Sample: quick-sort 1.2.0)."""


def quick_sort(a, lo=0, hi=None):
    if hi is None:
        hi = len(a) - 1
    if lo >= hi:
        return a
    pivot = a[hi]
    i = lo
    for j in range(lo, hi):
        if a[j] < pivot:
            a[i], a[j] = a[j], a[i]
            i += 1
    a[i], a[hi] = a[hi], a[i]
    quick_sort(a, lo, i - 1)
    quick_sort(a, i + 1, hi)
    return a

# Checks for quick_sort. To run them, set this file as the entry file
# (the ▶ button next to it in Files) and press Run.
from quick_sort import quick_sort


def numbers(seed, count):
    """Deterministic pseudo-random integers in [-50, 49]."""
    out = []
    for _ in range(count):
        seed = (seed * 1103515245 + 12345) % 2**31
        out.append(seed % 100 - 50)
    return out


cases = [[], [1], [2, 1], [1, 2, 3], [3, 2, 1], [5, 1, 5, 1, 5], [-3, 0, -1, 2]]
cases += [numbers(seed, size) for seed, size in ((1, 10), (2, 50), (3, 200))]

for case in cases:
    got = quick_sort(list(case))
    assert got == sorted(case), f"quick_sort({case[:6]}...) = {got[:6]}..."

print(f"All {len(cases)} checks passed.")