STL Internals: Containers and Algorithms

Analyze `std::vector`'s internal implementation, focusing on its capacity management and reallocation strategy.

Explain the iterator invalidation rules for `std::vector` during insertion and erasure.

Compare the memory layout and performance trade-offs of `std::vector` (contiguous) vs. `std::list` (node-based).

Analyze the internal data structures of `std::map` (red-black tree) and `std::unordered_map` (hash table).

Explain iterator categories (e.g., Input, Forward, Bidirectional, Random Access) and how they enable generic algorithms.

Apply move semantics with STL containers to efficiently transfer resources and avoid expensive copies.

Implement a custom allocator for an STL container to control its memory management behavior.