They are canned in a way, but they did first originate from these companies. Leetcode is essentially a compendium of all that. But you'll be nicked hard if you

They are canned in a way, but they did first originate from these companies. Leetcode is essentially a compendium of all that. But you'll be nicked hard if you don't communicate a ton. It's actually bad form to not verbally discuss the approach, big O space/time tradeoffs, testing approach, etc, before starting to code. For a medium type problem that could be a full 5-10 minutes of talking before doing 10-20 minutes of coding. Also the general advice is to not memorize the answers. There's literally thousands of them. It's to do many in different classes of problems to get a feel for the algorithms and to see the patterns on when to apply what, and to esp. dig deep into alternate solutions provided in the discussion sections because it's not uncommon for an interview to switch it up and ask to optimize space instead of time. It's really just becoming a mid-level competitive programmer, which takes some grit, but is somewhat removed from being a great engineer.