A Set of Water Jug Challenges

Question

You've probably heard about challenges with water jugs, so why not try a few?

Use 3- and 5- liter jugs to get 4 liters.
Use 5- and 7- liter jugs to get 4 liters.
This one's different. How many different exact measurements can you get using only 8- and 11- liter jugs (not including 0 liters)?
Use 3- and 11- liter jugs to get 7 liters.

These numbers are made by me, so if any of these exactly match the popular ones out there (except for the first one), it is purely coincidental.

Note: accepted answer is the one that is first with all 4 correct answers.

Format to submit answer

(example with 5- and 8- liter jugs to get 6 liters)
0-0, 0-8, 5-3, 0-3, 3-0, 3-8, 5-6

The God Damn Geek 'ANIMESH' · Accepted Answer · 2014-08-06T18:44:49.170

5

The answers are:

3-0, 0-3, 3-3, 1-5, 1-0, 0-1, 3-1, 0-4.
5-0, 0-5, 5-5, 3-7, 3-0, 0-3, 5-3, 1-7, 1-0, 0-1, 5-1, 0-6, 5-6, 4-7.
You can get 19 exact measurements (1 litre - 19 litres) not including 0 litre.
3-0, 0-3, 3-3, 0-6, 3-6, 0-9, 3-9, 1-11, 1-0, 0-1, 3-1, 0-4, 3-4, 0-7.

edited Aug 06 '14 at 18:44

answered Aug 06 '14 at 05:47

The God Damn Geek 'ANIMESH'

174
3

Ross Millikan · Answer 2 · 2014-08-06T19:41:42.223

4

For $1,2,4$ you can just fill one jug, fill the other from it, and repeat until solved. This will work for any jug contents as long as they have no common factor. If they have a common factor, you can only get multiples of the common factor. One direction will be faster than the other for a given target.

For 3, you can get any number from $1$ through $11$ in the $11$ jug, and have the $8$ full or not, so you can get anything $1$ through $19$, for $19$ values.

edited Aug 06 '14 at 19:41

answered Aug 05 '14 at 23:01

Ross Millikan

8,419
30
47

To clarify: 7 in either jug is still the same measurement, and the same goes for 6, 5, etc. – Vincent Tang Aug 05 '14 at 23:08
True, that is how I counted it. I was counting the number of total amounts of water in the two jugs that you can achieve. – Ross Millikan Aug 05 '14 at 23:45
I said in the question that 0 liters does not count. I just realized that error in your answer. – Vincent Tang Aug 06 '14 at 18:36
OK, fixed........ – Ross Millikan Aug 06 '14 at 19:41

score 3 · Answer 3 · answered Sep 14 '14 at 18:09

As I said in another post, the general solution for jug A and B is:

If A is empty, fill A
If B is full, empty B
else transfer what you can from A to B.
stop when you have the wanted quantity.

Depending on which jug you choose as A or B, you get 2 solutions. One of them is optimal.

score 1 · Answer 4 · answered Sep 17 '14 at 16:33

For number 3, here's a sequence that hits every number from 1 to 19:

0+0=0
0+11=11
8+3=11
0+3=3
3+0=3
3+11=14
8+6=14
0+6=6
6+0=6
6+11=17
8+9=17
0+9=9
8+1=9
0+1=1
1+0=1
1+11=12
8+4=12
0+4=4
4+0=4
4+11=15
8+7=15
8+0=8
0+8=8
8+8=16
5+11=16
5+0=5
0+5=5
8+5=13
2+11=13
2+0=2
0+2=2
8+2=10
0+10=10
8+10=18
8+11=19

score 0 · Answer 5 · answered Nov 23 '18 at 12:57

0

For 1:

0-5, 3-2, 0-2, 2-0, 2-5, 3-4

answered Nov 23 '18 at 12:57

JMP

35,612
7
78
151

A Set of Water Jug Challenges

5 Answers5

Linked

Related