Checkpoint: arrays, pointers, and windows
Cold recall
Three problems you have already solved, rebuilt from nothing.
Three problems from the last three units, in a different order than you met them and with no lesson above them telling you which pattern applies. Do not look at your earlier submissions. If you cannot start within a few minutes, that is information worth having now rather than in an interview.
Tip
What a slow one means
Taking a while is normal and fine. Not knowing where to begin is the signal that matters, and it means the pattern was recognized last time rather than understood. When that happens, finish the problem, then go back to the lesson it came from and read the invariant section again.
The review queue will bring anything you struggled with back on its own schedule, so you do not need to track this yourself.
Group Anagrams, cold
You have solved this one before. Rebuild it from scratch without looking at your old submission. If the approach does not come back within a few minutes, that is the signal that it needs another pass.
3Sum, cold
You have solved this one before. Rebuild it from scratch without looking at your old submission. If the approach does not come back within a few minutes, that is the signal that it needs another pass.
Minimum Window Substring, cold
You have solved this one before. Rebuild it from scratch without looking at your old submission. If the approach does not come back within a few minutes, that is the signal that it needs another pass.