If you equate constructive feedback with a dressing down, I can only feel sad for you.
"We noticed you used an unsorted list, where a dictionary/map would've been a natural fit. Based on this we don't feel confident that you have the mastery of algorithms that we require for this job. We suggest you take time to brush up on your algorithms by reading the first volume of The Art of Computer Programming by Donald Knuth or the first three chapters of Algoritms by Robert Sedgewick. We believe this will also help you in your future career at other companies. We wish you good luck in you job search."
If someone gets mad by that, that says a lot about their character and how much you never want to have them in your team. Also other people will either know their character and discount their opinion or will not, which means they will self-select themselves out of your candidate pool, which I see as a positive.
"We noticed you used an unsorted list, where a dictionary/map would've been a natural fit. Based on this we don't feel confident that you have the mastery of algorithms that we require for this job. We suggest you take time to brush up on your algorithms by reading the first volume of The Art of Computer Programming by Donald Knuth or the first three chapters of Algoritms by Robert Sedgewick. We believe this will also help you in your future career at other companies. We wish you good luck in you job search."
If someone gets mad by that, that says a lot about their character and how much you never want to have them in your team. Also other people will either know their character and discount their opinion or will not, which means they will self-select themselves out of your candidate pool, which I see as a positive.