FREE Interview mastery LESSON · Interview mastery
Make correctness visible
Contracts, invariants, and executable communication
Narrate decisions, not keystrokes.
Restate the contract, test ambiguity with examples, name the dominant operations, and compare plausible representations. Once you choose, state the invariant before implementation. While coding, connect each block to that invariant. Finish with boundary cases, complexity under the stated model, and a small trace.
Communication is not decoration; it exposes assumptions early enough to correct them.
Pattern recall fails when the surface changes.
Memorized templates help only when their preconditions are understood. Ask what state must be preserved, which operation dominates, and what information becomes available over time. If a solution fails, diagnose the missing model—not merely the pattern name—and route practice to that prerequisite.
The transferable unit is an invariant plus the conditions that make it useful.