Triangle Classifier QA Puzzle

Classifying a triangle by the lengths of its three sides is a classic junior-QA interview exercise. Each side goes in its own field, and the program answers with one of four verdicts: equilateral, isosceles, scalene, or not a triangle.

This particular implementation is deliberately buggy. Your job is to design test cases, find inputs where the program gives the wrong answer, and cover the important equivalence classes and boundary values. The trackers below count how many planted bugs you have found and how many canonical test cases you have exercised at least once.

• Progress lives only in this browser tab and resets when you reload.
• You can also test the program directly as an API: POST /api/check with {"a":"3","b":"4","c":"5"}, or GET /api/check?a=3&b=4&c=5.