Linear Search

# Linear Search

Zerethon Official Sample `linear-search`, version 1.1.0, Python 3.12.

- `linear_search.py` — the algorithm, as shown in Zerethon Tools
- `main.py` — entry file: a short demonstration
- `test_linear_search.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/linear-search-visualizer

"""Linear Search (Zerethon Official Sample: linear-search 1.1.0)."""


# Returns the index of target, or -1. Works on any (unsorted) list.
def linear_search(a, target):
    for i in range(len(a)):
        if a[i] == target:
            return i
    return -1

from linear_search import linear_search

numbers = [38, 27, 43, 3, 9, 82, 10, 27]
print("List:", numbers)
for target in (43, 27, 38, 5):
    index = linear_search(numbers, target)
    result = f"found at index {index}" if index != -1 else "not found"
    print(f"search {target:>2}: {result}")

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

cases = [
    ([], 1, -1),
    ([4], 4, 0),
    ([4], 5, -1),
    ([9, 3, 7], 9, 0),
    ([9, 3, 7], 7, 2),
    ([5, 1, 5, 1], 1, 1),  # the first match wins
    (list(range(100, 0, -1)), 1, 99),
]

for a, target, expected in cases:
    got = linear_search(a, target)
    assert got == expected, f"linear_search({a[:5]}..., {target}) = {got}, expected {expected}"

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