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Programmer tries to explain binary search to the police (startrek.website)

submitted 1 year ago by The_Picard_Maneuver@startrek.website to c/programmer_humor@programming.dev

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[-] CosmicCleric@lemmy.world 3 points 1 year ago* (last edited 1 year ago)

But you will see the event happen though.

Not with a binary search.

Yes you will.

A binary search is just what it says, it's just for searching only.

When you find that moment in time where the bike was there one moment, and then the next moment the bike's not there, then you view at regular or even slow-mo at those few seconds of the bike in the middle of disappearing, and see the perpetrator, and hopefully can identify them.

[-] Azzu@lemm.ee 33 points 1 year ago* (last edited 1 year ago)

You didn't get what was talked about here. Re-read the topmost parent comment.

How do you binary search for two people arriving, one punches the other, they both leave?

[-] CosmicCleric@lemmy.world 2 points 1 year ago* (last edited 1 year ago)

You didn’t get what was talked about here. Re-read the topmost parent comment.

I was responding to this ...

Part of my job is to review security footage for reported incidents.

If there is a long-lasting visual cue that the event has or has not happened yet (e.g. a window is either broken or not), then a binary search is very useful.

If the event lasts only a moment and leaves no visual cue (e.g. an assault), then binary search is practically useless.

I disagree with the "leaves no visual cue" part, as I've commented on. There's ALWAYS something caught on the video to help determine things. Maybe not enough, but never nothing.

[-] LUHG_HANI@lemmy.world 7 points 1 year ago

Maybe I'm not understanding both arguments here but I'd like to understand. I've had to review footage of a vending machine being shaken to release drinks.

You have no before or after visual clue as to when the event took place. The only indication is when you physically see it happening. The same could be said for an assault. If nothing is changed in the before or after static still how can you pinpoint the incident?

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[-] ShrimpsIsBugs@programming.dev 13 points 1 year ago

You either don't know what binary search is or you completely missed the context of this conversation

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[-] lustyargonian@lemm.ee 12 points 1 year ago

Binary search only works on sorted data, i.e. you know which side of the mid point is pointing towards the incident. If the incident leaves no trail, you can't know whether you can discard the left side or the right side, making it a complicated linear search at that moment.

[-] CosmicCleric@lemmy.world 2 points 1 year ago

If the incident leaves no trail, you can’t know whether you can discard the left side or the right side

There's a moment where the bike is there, then another when its not. The whole video, either way, will either from the beginning up to the point of theft have the bike there, or NOT have the bike there from the point of theft to the end of the video. The marker is the removal of the bike from the video lens.

[-] starman2112@sh.itjust.works 9 points 1 year ago

But the comment you replied to wasn't talking about bike thefts specifically, it was talking about unspecified situations that don't leave traces. You responded to someone saying that binary search doesn't work in situations that don't leave cues not by arguing against the premise (e.g. "but no such event exists, everything leaves cues"), but by telling them that you simply have to look for the cues from the hypothetical event that didn't leave any.