It would be fun for a grade school or highschool teacher to actually give this riddle to his or her kids to solve as extra credit in math.
1, 2 Freddy's coming for you. 3, 4 better lock your door.

"I do not like mixing up moralities and mathematics."
Churchill

Today I was watching the movie, and before they solved it in the movie, which I have no idea how they did, I think that if you fill the five gallon jug full, then pour it all over into the three jug, you get 2 gallons remaining DAMNIT I need two three gallon jugs for my solution to work because you need to do that two times. False alarm everybody. I didn't solve it.

Best way to do it though is to fill the 3 gallon jug, then empty it into the 5 gallon jug. Then repeat, fill 3 gallon jug and empty into 5 gallon jug. 5 gallon jug will be filled leaving 1 gallon of water left in the 3 gallon jug.
Then empty out the 5 gallon jug. Pour the 1 gallon of water from the 3 gallon jug into the 5 gallon jug and then refill the 3 gallon jug again and pour that into the 5 gallon jug giving you exactly 4 gallons of water in the 5 gallon jug.
That is the simplist way of doing that. The way they did it in the movie is more complicated. Here is how they did it.
They fill the 5 gallon jug to the top. They fill the 3 gallon jug with said 5 gallon container. They now have 2 gallons in the 5 gallon jug. Pour out the 3 gallons in the 3 gallon jug. Pour the 2 gallons into the 3 gallon. Fill the 5 gallon jug and dump 1 gallon into the 3 gallon jug filled with 2 gallons to get 4 gallons. Obviously the film makers wanted to use the more complex method. Also the method the guy above used would've taken a little less time as it involves dumping 9 gallons as opposed to the one they used in the movie that involves dumping out 10.
1, 2 Freddy's coming for you. 3, 4 better lock your door.

no the easiest is fill the 5. fill the 3 from the 5. empty the three. pour the 2 left in the 3 gallon. fill the 5 again dump out the gallon into the 3. much faster.

Yes, I came here to write down that very same solution.

Best way to do it though is to fill the 3 gallon jug, then empty it into the 5 gallon jug. Then repeat, fill 3 gallon jug and empty into 5 gallon jug. 5 gallon jug will be filled leaving 1 gallon of water left in the 3 gallon jug.
Then empty out the 5 gallon jug. Pour the 1 gallon of water from the 3 gallon jug into the 5 gallon jug and then refill the 3 gallon jug again and pour that into the 5 gallon jug giving you exactly 4 gallons of water in the 5 gallon jug.

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they don't show John and Zeus doing all the process
May be not to save time, but the solution they come up with is correct.

in the movie they don't show John and Zeus doing all the process

I had a good buzz on while I was watching it last night but I made myself think about how to do it over and over (through the confusion) til I had the first method figured out. Had it down first thing this morning. Second way is better though, hadn't thought about that way. Ty for the response
"I do not like mixing up moralities and mathematics."
Churchill

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