Overthinking the rules; Off-by-one riddle

Meme contest

There is still a meme contest on. It is important that I tell you and to write a little about it because one of the prizes listed is:

1 HiveSBI for every Blog post on Hive about the meme contest!

So there you go @slothbuzz, time to send one more HSBI my way. 😋

So far the competition is not very big, only dilligaf (don't know the hive tag) and @acidtiger besides @slothlydoesit are active.

My latest meme is based on a screenshot from Big Bang Theory:

But mostly I try to use my own images. Here is one of those:

Contest rules

To win the contest, I have to post a (new and unique) meme in the #slothbuzz discord channel for that contest and be the last poster for 24 hours.

Sounds easy enough and is easy enough and that is why my brain made it complicated.

Let's make it complicated

I was thinking (or not, that will turn out to be the problem), that when I post my meme, I have to make sure of the timing. Within 24 hours my meme must be the last.

I have to post at a moment so that 24 hours later I could, if needed, post again.

Whenever someone else posts the 24 hours start again. That tiny bit of information did somehow not get processed by my brain.

What I was thinking and fearing was that someone might be "sniping" the 24 hours. Meaning that if I post at 4pm they would sit there and hit the send button at 3:59pm shortly before 4pm the next day.

A few seconds later 24 hours were up, mine had not been the last and I would have lost.

Uh, that was bugging me. I was even considering "reloading", so to speak. Posting another theme after my last one, if I realized, I would not make the deadline the next day.

I started to ask questions to get a feeling for the rules. Trying to figure out how to beat this thing.

Epiphany

At some point two days ago it finally hit me and that last bit of information was properly processed by my brain.

So even if someone "snipes" (who knows, maybe they like the thrill), at that very moment the 24 hour clock resets for me to post. So in the end: Whenever I check, regardless of how long ago I posted my meme, as long as I was the last, at that moment I have guaranteed 24 hours time to respond (in case they post directly after me closing the discord).

Relax

With that out of my head now, I can relax again. Yet it reminded me of another puzzle based on the typical off-by-one error our math teacher gave us in the 90's.

Off-by-one

The off-by-one error/mistake applies for example when you plan how many pickets you need for a fence. Let's say you want a picket every 15cm (yes, I use metric units 100cm=1m) and the fence is 3 meters (that's 300cm) long.

Indeed, you need 21 pickets. If you thought 20 (because 300/15=20) then you fell victim to the off-by-one error because you forgot the starting picket.

Same goes for ladders. It starts with a bar at zero position (bottom) and ends with a bar at the top. So a 2 meter (200cm) ladder with a bar every 20cm needs 11 bars.

A riddle

When we discussed the off-by-one mistake in class (I think it was 9th grade) our math teacher gave us a riddle.

There is a ship in harbor with a ladder attached reaching down into the water.

The ladder has a bar at both ends (we just talked about that some paragraphs earlier) and the space between the bars is 20cm. The ladder is 3 meters (300cm) long and right at this moment the lowest bar is just barely covered by water.

Lucky for us it is low tide and it takes (we make it easier to calculate by giving nice numbers) 6 hours to get to high tide and then again 6 hours to get to low tide again. So after 12 hours we are back where we started.

Yes, let's forget the wind and rain and far fetched ideas like earthquakes, hurricanes and all that stuff.

Ok, we will make it just a little bit easier, let us assume a steady up and down during the tides. Forget that (co)sinus stuff.

Now the question is, how many bars are covered with water after
20 hours?

I know, I know

Good for you, you saw through this right from the beginning. But please, let those who want to do some math post their solution in the comments first. 😉

Have a nice day

That was my sloth post for the day, I hope you enjoyed reading it as I enjoyed writing it. I tried to include some of the memes I posted for the contest.

The ones based on pictures taken by me can be used freely without need for sourcing or crediting.

See you next time.

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Header image picture taken by me.
"I posted a meme in slothbuzz" meme based on Screenshot from "The Big Bang Theory".
"Killer Duck" meme picture taken by me.
"Really?" meme picture based on screenhot from "Columbo".
"Scratch That" meme picture taken by me.
"Who are you kidding?" meme based on screenshot from "Columbo".