“This exact problem” isn’t the packing problem discussed in the OP, right? It’s a different problem about taking the union of overlapping rectangles with their bottom edges at the same vertical position.
Reading just the headline, I thought that's what this post was referring to. I used to give the Skyline overlapping rectangle problem at Google for several years, until it got banned. I'd say that with appropriate nudges, most candidates were able to get through it in an hour. I don't know how things have changed since 2015, but this was all on a whiteboard, so at least there wasn't time wasted fighting a compiler.
Then again, my lifetime stats on interviewing at Google, measured by interview scores vs eventual offers extended was somewhere between noise and a slightly negative correlation, so I never did figure out why they let me interview at all! (I think I'm too nice in interviews, because I want everyone to succeed, and asking myself "if this person were on my team, would I be as happy to collaborate with them as I would be with Nick? Really?" only goes so far in counteracting that.)
Then again, my lifetime stats on interviewing at Google, measured by interview scores vs eventual offers extended was somewhere between noise and a slightly negative correlation, so I never did figure out why they let me interview at all! (I think I'm too nice in interviews, because I want everyone to succeed, and asking myself "if this person were on my team, would I be as happy to collaborate with them as I would be with Nick? Really?" only goes so far in counteracting that.)