CMP.3:8 - Common Anti-Patterns and How to Avoid Them

Misstep exposed by the method	Consequence and repair
Key a subproblem by its position across changing inputs	The edit-distance example reuses an answer to another question. Bind the key to the input and conditions or narrow the cache’s lifetime.
Treat an in-progress entry as an answer	A cyclic dependency can return unsupported content. Keep completion explicit and supply the appropriate cycle-solving method.
Discard predecessors while promising a witness	The optimum value remains but the attaining object cannot be returned. Retain choices or construct a reconstruction pass.
Share effects as if they were pure calculations	Observations, updates or random dependence can change. Identify the fixed data calculation that is actually interchangeable.