Both approaches work for bucket puzzle - IdeaWhiz got them

#1
by SubtleOne - opened

Here is what IdeaWhiz came up with, and both work:

Output: So I have this problem here: I've got two buckets, one holds 2 gallons and the other holds 5 gallons. I need to end up with exactly 4 gallons in one of them. Hmm, sounds like a classic puzzle. I remember these from somewhere, maybe high school or something. Anyway, let's see how to approach this.

First, I need to understand what operations I can perform. It seems like I can fill a bucket to its full capacity, empty a bucket completely, and pour from one bucket to another. That's probably it. So, my actions are limited to filling, emptying, and pouring between the buckets.

Let me denote the buckets for clarity. I'll call the 2-gallon bucket Bucket A and the 5-gallon bucket Bucket B. Starting off, both are empty.

My goal is to have exactly 4 gallons in one of the buckets. Since Bucket A is only 2 gallons, I can't have 4 gallons in there. So, I must aim for Bucket B to have exactly 4 gallons.

Alright, let's think step by step.

  1. Fill Bucket B (the 5-gallon bucket) to the top.

Now, Bucket B has 5 gallons, and Bucket A is still empty.

  1. Pour from Bucket B into Bucket A until Bucket A is full.

Since Bucket A holds 2 gallons, I can pour 2 gallons from Bucket B into Bucket A. Now, Bucket A has 2 gallons, and Bucket B has 5 - 2 = 3 gallons left.

  1. Empty Bucket A.

Now, Bucket A is empty again, and Bucket B has 3 gallons.

  1. Pour from Bucket B into Bucket A until Bucket A is full.

Bucket A can hold 2 gallons, and Bucket B has 3 gallons. So, I pour 2 gallons from Bucket B into Bucket A. Now, Bucket A has 2 gallons, and Bucket B has 3 - 2 = 1 gallon left.

  1. Empty Bucket A again.

Now, Bucket A is empty, and Bucket B has 1 gallon.

  1. Pour the 1 gallon from Bucket B into Bucket A.

Now, Bucket A has 1 gallon, and Bucket B is empty.

  1. Fill Bucket B to the top again.

Now, Bucket B has 5 gallons, and Bucket A has 1 gallon.

  1. Pour from Bucket B into Bucket A until Bucket A is full.

Bucket A can hold 2 gallons, and it already has 1 gallon. So, I need to add 1 more gallon to fill it. Therefore, I pour 1 gallon from Bucket B into Bucket A. Now, Bucket A has 2 gallons, and Bucket B has 5 - 1 = 4 gallons.

Final state: Bucket A has 2 gallons, and Bucket B has 4 gallons. Success! I have exactly 4 gallons in Bucket B.

Let me just double-check if there's a more efficient way or another way to do this.

Alternative approach:

  1. Fill Bucket A (2 gallons) and pour it into Bucket B.

  2. Repeat step 1 until Bucket B is full.

  • So, fill Bucket A (2 gallons) and pour into Bucket B. Do this twice: 2 + 2 = 4 gallons in Bucket B.

  • But wait, Bucket B holds 5 gallons. If I pour 2 gallons twice, that's 4 gallons, which is what I want. So, in this case, I stop at 4 gallons without filling Bucket B to its full capacity.

Is that acceptable? The problem says "fill one of the buckets with exactly 4 gallons." It doesn't specify that the bucket has to be filled to its full capacity, just have exactly 4 gallons in it.

So, yes, this alternative approach works too and is simpler:

  • Fill Bucket A (2 gallons) and pour into Bucket B.

  • Repeat once more: fill Bucket A and pour into Bucket B.

  • Now, Bucket B has 4 gallons.

That's even better. So, there are at least two ways to achieve exactly 4 gallons in one of the buckets.

First method:

  1. Fill B to 5.

  2. Pour 2 to A.

  3. Empty A.

  4. Pour 2 to A from B.

  5. Empty A.

  6. Pour remaining 1 to A.

  7. Fill B to 5.

  8. Pour 1 to A to fill it, leaving 4 in B.

Second method:

  1. Fill A to 2.

  2. Pour to B.

  3. Fill A to 2 again.

  4. Pour to B, making B have 4 gallons.

So, the second method is definitely more straightforward. I wonder if there are more ways to do this.

Another way:

  1. Fill B to 5.

  2. Pour 2 to A.

  3. Empty B.

You know what? I never let it go all the way down because it seemed like a bad solution. I'll have to start letting gen's go all the way.

Out of curiosity, what quant level did you test this with?

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