Stacks (FILO) and queues (FIFO) model expression parsing, backtracking, and history navigation. Use arrays as stacks, and emulate queues with circular buffers or two stacks when necessary.
- Push on opening tokens and pop on matching closers; keep a map of pairs for clarity.
- Evaluate expressions by using stacks for operands/operators and handling precedence explicitly.
- Simulate queue behavior (for BFS or caches) with arrays or linked lists when built-in queues are unavailable.