- Quick Sort
Partition around a pivot and recurse. Sorts in place and is usually the fastest in practice, but has an O(n^2) worst case — and the input that triggers it is the already-sorted array you are most likely to be handed. Median-of-three, and the recursion trick that caps the stack at O(log n).
- Spring Boot – Async Work and Thread Pools
@EnableAsync, @Async and a ThreadPoolTaskExecutor sized on purpose rather than left at the default. What the queue and rejection policy actually do under load, @Scheduled for recurring work, and why an @Async method that returns void throws away its own exceptions.
- iOS – Forms, Text Input and Validation
The keyboard is part of your UI. keyboardType, textContentType and AutoFill, the autocapitalisation default that breaks every email field, @FocusState and moving between fields, and a validation model that keeps the rules out of the view and testable in microseconds.
- Python – Exception Handling
try, except, else and finally, catching the exception you meant rather than all of them, raising your own, chaining with `raise ... from`, and why a bare `except:` is the line that hides the bug you are looking for.
- Frontend Dev – What a Frontend Engineer Actually Does
The job, described by what lands in your queue rather than by a job posting. What you own — the interface, the state behind it, what happens on a slow phone, and whether somebody using a keyboard can get through it — where the line sits between you and design, backend and QA, and what a real ticket looks like from mockup to deploy.