Compile Time Index Access

Compile-time index access with template metaprogramming

This hard C++ problem tests your ability to implement compile-time logic using template specialization and metaprogramming. Rather than computing a result at runtime, you must define a struct whose value member is evaluated and verified by the compiler itself through static_assert.

The core challenge is designing a template that safely retrieves an element from a variadic template pack at a given index, with proper bounds checking. You'll need to handle edge cases including negative indices and out-of-bounds accesses—all without any runtime branching. The solution typically involves recursive template instantiation or specialization patterns that the compiler can fully resolve before your program runs.

• Variadic template parameters and pack expansion
• Template specialization and partial specialization
• Compile-time conditionals via template traits
• Index-based element extraction from parameter packs