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

submitted 11 months ago by The_Picard_Maneuver@startrek.website to c/programmer_humor@programming.dev

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[+] CosmicCleric@lemmy.world -31 points 11 months ago* (last edited 11 months ago)

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

In the same way the OP talks about it ...

You don't watch the whole thing, he said. You use a binary search. You fast forward to halfway, see if the bike is there and, if it is, zoom to three quarters of the way through. But if it wasn't there at the halfway mark, you rewind to a quarter of the way though. Its very quick. In fact, he had pointed out, if the CCTV footage stretched back to the dawn of humanity it would probably have taken an hour to find the moment of theft.

Instead of a bike, you look for the aftereffects of a fight happening (chairs knocked down, tables turned over, etc.). You can even look at how many people congregate around the location of the fight before and after the video as a 'marker' to the point of time the fight was happening/just finished.

Edit: One thing we didn't even mention, AI can also be used these days to notice subtle changes in the video. If a video is a static image of an alley, then two people walk in the alley and fight, even though they leave no traces behind, that moment of the fight is caught on the video with activity/movement. Motion sensor movement, basically.

[-] Kialdadial@iusearchlinux.fyi 9 points 11 months ago

Your adding things that would allow a binary search work, but the question was in a situation where the only evidence is the conflict itself

2 guys enter one guy punches the other guy they both leave. Nothing is moved no blood was created,

you could not use a binary search effectively to duduce when it occurred.

[+] CosmicCleric@lemmy.world -19 points 11 months ago* (last edited 11 months ago)

Your adding things that would allow a binary search work, but the question was in a situation where the only evidence is the conflict itself

I'm describing the vast majority of fights that happen in the public. Also, you're trying to move the goalposts by focusing on a fight, when the discussion is about the theft of a bike.

Edit: One thing we didn’t even mention, AI can also be used these days to notice subtle changes in the video. If a video is a static image of an alley, then two people walk in the alley and fight, even though they leave no traces behind, that moment of the fight is caught on the video with activity/movement. Motion sensor movement, basically.

[-] Kialdadial@iusearchlinux.fyi 9 points 11 months ago

What does that have to do with a binary search If a camera has AI on it then two things. A you have a system that already would be capturing movement or motion so you already have flags that you can check which would make a binary search mostly unnecessary. and B it's not binary search. Which is this whole discussion.

Cool you're adding information to the question to make yourself "right" but even your comment says that's only the vast majority of fights and also you had to clarify in public so there are edge cases where the situation still stands that binary search wouldn't work or wouldn't be feasible.

A solution doesn't have to work for 100% of things for it to still be a good solution.

[+] CosmicCleric@lemmy.world -10 points 11 months ago

Cool you’re adding information to the question to make yourself “right”

No, I'm not. Within the moment I'm creating a comment I might save and then edit, because in the past I lost whole comments when I switch tabs in my browser. But when I'm done and hit that save I'm done, and then a few cases when I'm not I add an "Edit:" to it.

but even your comment says that’s only the vast majority of fights and also you had to clarify in public

Well most fights are in public, if a public camera is recording it. If a fight is private then it's probably not being done where a camera is.

so there are edge cases where the situation still stands that binary search wouldn’t work or wouldn’t be feasible.

The only edge case I could think of would be if something happens in a split second and then the scene is static again, the same before and after that.

But even then if you're talking about a static scene on the camera AI would probably be able to catch that split second change happening, so binary searching can still be done.

[-] Kialdadial@iusearchlinux.fyi 6 points 11 months ago

I have a feeling you just don't understand how a binary search functions even with AI you wouldn't be using a binary search at that point

If you have camera footage from 4pm to 8pm with event lasting 1 minute but no changes occur to the background/foreground how exactly are you using recursion to determine which part of the footage even occurred without going through the entire film. Are you picking at random?

The way you're describing AI is not binary search and so it can't be used in this example. Also most public cameras are not 8K cameras they don't contain a lot of detail, so the argument that they could catch something subtle kinda gets blown out of the water. You can't just use AI as a cop out for not understanding how function behaves or works