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Programmer tries to explain binary search to the police
(startrek.website)
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this post was submitted on 30 Nov 2023
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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.
But you will see the event happen though.
It's a matter of if you can identify who the perpetrator is or not, but at least that due diligence should be done by police, looking at the person doing the crime and see if they can be identified.
Not with a binary search.
Edit: just collapse this thread and move on. Cosmic Cleric is an obvious troll.
Well now I HAD to read the thread
What an absolute weirdo.
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.
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?
In the same way the OP talks about it ...
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.
You are seriously confused. OP specifically said that you're fucked if there is no visual cue.
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.
What about this hypothetical scenario:
Suppose the objective is to review highway cam footage of the day to verify that a (non-speeding) car with a particular license plate drove past the area / used this route. The route is used 24/7 by many identical cars throughout the day and night, and that our target car is one such identical car, with the only difference being the license plate. We know on average cars that drive past this camera only appear for 3 seconds on the footage. How can binary search be used to find the car within 24 hours of footage, if the target car only appears for 3 seconds within the 24 hour video?
You either don't know what binary search is or you completely missed the context of this conversation
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.
That doesn't apply to the comment you replied to.
Let's use the example of a bike theft. We enter into evidence a 4-hour security cam video that shows the thief with the bike.
Scenario A: The camera can directly see the bike rack, and the bike in question is visible at the beginning of the video, and not visible at the end. Somewhere in this 4-hour video, someone walks up to the bike and takes it out of the bike rack. You can use a binary search to find the moment that happens in this video because you can pick a frame and say "Ah, this was before the theft; the bike is still there" or "ah, this was after the theft; the bike is gone."
Scenario B: The camera can't directly see the bike rack, but can see the doorway you have to walk through to get to the bike rack. So somewhere in 4 hours of doorway footage, someone walks through the door, then a short time later walks back through the door with the bike. A binary search won't help here because the door looks the same at the beginning or end of the video. A simple binary search won't work here because the door looks the same before and after.
This is the explanation that CosmicCleric needs in order to understand binary search.
Because as it is, (s)he’s failing abysmally at demonstrating any understanding whatsoever of that subject.
Nah, they're just gonna say you can use AI or something, as a retroactive explanation for what they obviously weren't talking about in their original comment. They're a troll; they're not going to budge.
Edit: Case in point. They're now at the level of mental gymnastics that they're saying part of their original response implied that they were talking about the capabilities of AI at some point in the future.
I'm just a random guy stumbling across this thread hours after the fact. I want to say that after reading many of these comments. I feel like I'm starting to get a handle on what your position is. You aren't wrong, but you are communicating your idea horribly.
Your position seems to be "Thankfully, many crimes do leave behind lasting visual cues, so you can still do a binary search for those situations if you are clever about what to look for."
What you've actually been communicating is that "If there really was no lasting visual cue, then just find a lasting visual cue anyway, then do a binary search on that and it'll work!" - It's all about how you choose to present, order, and emphasize your comments. Your message is more than just the words you type. I hope this message helps clarify the debate and confusion for you and anyone else who stumbles upon this long chain.