Java, OOP & Design

Intuit's coding loop is unusual in what it rewards. The algorithms sit at easy to medium, and finding the optimal answer is rarely what decides a round. What decides it is craftsmanship: whether the classes are clean, the invariants are guarded, and the tests are already written when the interviewer asks for them. The Craft Demo makes this explicit, and the Assessor round backs it up, pivoting from a data-structure answer into how you would design and test the same thing in Java. The craft is the exam.

So this lesson builds the design-and-testing muscle those rounds grade. You will practice naming an interface before typing a method, hiding state behind operations that enforce their own rules, and reaching for composition instead of a deep inheritance tree. The interview language is almost always Java or Spring Boot, and the panel wants code it would put on its own GitHub. We model the three problems below in Python to keep the logic short, and name Java as the language you would write in the room, because the habits carry across both.

The Intuit angle

At Intuit the craftsmanship bar is a graded axis, weighted like any other. Candidates describe the Craft Demo panel as adversarial, deliberately hunting for holes: a hardcoded value, a missing test, a class that cannot absorb the next feature. That is what the round tests. A component that stays clean through three follow-ups beats a clever one that cracks on the first extension. JUnit controller and service tests count as a deliverable here, ranked alongside the code itself. Get the design clean and the tests written, and you have shown the exact instinct the loop is built to find.