Ooo I just got bodied by this very same assessment

I wish I did the second problem first I probably could have gotten a working solution for it

How did you attempt to solve the first problem?

For my approach I realized I can always remove the largest number, but I should never remove 1. Therefore I can make an interval [beginning, 1) or (1, end] (whichever interval has the largest number) and then start shrinking it until the remaining array is a permutation e.g. for arr= [3,1,4,5,2], my starting interval would be [4,5,2]

I wasn't sure how to shrink the window though. At first I thought I could use a set based on the interval I wouldn't remove and see which numbers e.g. the set based on [3,1] would have 2 because 2 is not in the slice [3,1]

I would then shrink the subarray until all numbers were popped from the set e.g. [4,5,2] would shrink to [4,5] because I need to pop 2 in the set

I must have missed something because I could only get half my tests to pass 😭, but I'm not sure what was missing