Day 29: The bridge riddle (with conditionals)
Well hello there!
We're so very close to the end! I had initially thought that the last week would be a reprise of "the best" challenges (who can determine which are the best, anyway?), but as time went by I kept finding new things I wanted to include.
Some challenges, however, were very enjoyable to me personally, so there is no way I couldn't revisit them. One of such challenges was the riddle. And so here it is again! A new one, of course.
The idea behind this riddle challenge is the following:
- Try to solve the challenge (but of course!)
- Explain your thought process, whether you reached a solution or not. What was your initial idea? Did you change your mind? How did you find the answer, if you did?
- Here comes the conditional part: what other solutions would have been possible if one or more of the conditions set in the riddle had been different? In other words, how do the results vary if the riddle proposition changes? (Note: there are many conditions you could change here, so don't sweat it, you don't have to exhaust all the possibilities.)
Enjoy the thinking, the explaining and the hypothesising!
We're so very close to the end! I had initially thought that the last week would be a reprise of "the best" challenges (who can determine which are the best, anyway?), but as time went by I kept finding new things I wanted to include.
Some challenges, however, were very enjoyable to me personally, so there is no way I couldn't revisit them. One of such challenges was the riddle. And so here it is again! A new one, of course.
The idea behind this riddle challenge is the following:
- Try to solve the challenge (but of course!)
- Explain your thought process, whether you reached a solution or not. What was your initial idea? Did you change your mind? How did you find the answer, if you did?
- Here comes the conditional part: what other solutions would have been possible if one or more of the conditions set in the riddle had been different? In other words, how do the results vary if the riddle proposition changes? (Note: there are many conditions you could change here, so don't sweat it, you don't have to exhaust all the possibilities.)
Enjoy the thinking, the explaining and the hypothesising!
Hi, Bea,
ReplyDeleteI solved it, but I had to change my first idea. Initially, I thought that the fastest should cross with the slowest, and so he could come back quick. However, that way the times didn´t fit and I had to devise a new plan. Then I realized that the two slowest should cross together and once to minimize the waste of time they took. Moreover, the two fastest should cross in first place for them to be the ones who took the lantern back in turns. And so, the final solution came up.
In the original proposal it takes the zombies 17 minutes to reach the bridge, and if they get there and you haven´t completely crossed it you die. But, what if that premise were different? what if when the zombies reached the nearest side of the bridge one person had already started to cross and he were, let´s say, in the middle? Depending on who he were, he might get to the other end of the bridge on time not to be caught. Obviously, we would need to know how much time it would take the zombies to cross the bridge. Anyhow, this way there would be more correct combinations to solve the riddle.
Bye!
Hi mates!
ReplyDeleteThis challenge reminded me that I had the first riddle pending to be solved, so tonight I solved not one but two riddles! :-)
As for my thinking process, I started calculating how much it would take them to cross the bridge if the fastest person took part in every crossing. After realizing that the sum of the total time was invariant regardless of the order in which the other characters would cross (19 minutes) I thought I should minimize this time by making the two slowest character go together. It was a light-bulb moment when I realize that these two slowest character couldn't cross in the first place as it would take us a long time to have the fastest (five-minutes character) back in the beginning of the bridge. :-)
The condition I'd like to change is adding the existence of a lighthouse at the end of the bridge which would light the second half of it. This means that the use of the lantern would only be needed for the first half of the bridge. If the second part of the bridge had had illuminated, the two slowest character could have gone in the first place. When reaching the middle of the bridge, the slowest character would have kept going towards the end of the bridge while the 5-minutes character would have returned to the beginning of the bridge. After that, the 5-minutes character and the two-minutes character would have gone to the middle of the bridge, the slower one would have then advanced until the end of the bridge, while the slower one would have been back to the beginning. Lastly, after waiting for one minute for the 5-minutes character to have reached the end of the bridge, the two fastests character would have walked the whole bridge. This way it would have also taken them 17 minutes.
Thank you Bea! I love riddles and had fun solving both of them!
Can't believe we have just one day left!
Hi mates!
ReplyDeleteI've solve the riddle in a different way, with a little variation.
What is clear is that the two slowest people should cross the bridge together and just once, so the first logic step is to go with the lab assistant to the other end of the bridge (2 minutes). Then (that's the difference), to send back the assistant with the lantern (4 minutes) so, that it can be given to the janitor and the professor in order to cross the bridge (14 minutes). Once they have arrived, to cross the bridge (15 minutes) to meet the assistant and finally to happily return with her (17 minutes) safe and sound.
What I personally consider an interesting modification is to reduce the time it takes for zombies to arrive, for instance 16 minutes, to create a no-win scenario. What kind of decisions would people make under such circumstances? To sacrifice the professor because he's the oldest one? Or perhaps the janitor because he has a low qualification job and he's replaceable?
See you tomorrow!
Hi everyone!
ReplyDeleteI must admit I had seen this riddle some time before, and when trying to solve it, I've tried to remember what the solution was. But…. this has resulted in a very tricky strategy! I remembered that there was someone crossing together, someone crossing back... And believe me, this was not the best way to solve it, as I was so focused trying to remember that, that I forgot the condition of the lantern! I was so happy that I had two minutes left… LOL!
So, my false answer to the riddle was the following: the first ones to cross the bridge are the two slowest men, then I go for the lantern (and here was my mistake: I would have need the lantern! Oh, my God!) and then I run back to go for the lab assistant. Finally, we both make the final crossing.
Here is my question: what if we would have need a light to cross the bridge at night, but we hadn't found any?? HAHAHAHA! Maybe we could take into consideration that we would have been able to guide us touching the rope, as the divers do when they submerge in underwater caves.
See you now!
I must confess that I looked a bit the answers of my mates, but I obtained the solution (quite earlier than expected, because I'm really bad at riddles haha). On the first trip, the two fastest would cross the bridge, in 2 minutes. Then, our character would be back at the beginning to give the lantern to the janitor and the elder professor. They would take ten minutes to cross. After arriving the other side of the bridge, they would give the lantern to the lab assistant, that in two minutes would be back to our position to cross for the last time the bridge in two minutes, with a total amount of time of 17 minutes spent. The zombies will reach the beginning of the bridge, but no one else would be there. As I suppose, they would not be very smart, so they would try to enter to the bridge all at the same time, so the bridge would collapse and we wouldn't even need to cut the rope to escape from them. Anyway, there would be time to do so.
ReplyDeleteA question that I have is: If it is a straight-line bridge, why do they need lights? Why can't they just go grabbing the rope? That would have meant extra time to cross for everybody, and without a change of the time for escaping, would have opened the dramatic question of who is left behind: Ourselves, the intern that has just arrived and let the zombies escape by mistake? The lab assistant, whose job you would take after that? An old professor who has given everything he could to science and had lived an almost entire life? Or the janitor, with no qualifications?
Thnks for sharing all those challenges!