Water Jug
Published in Brain Teasers
You have a four-liter jug and a nine-liter jug. You also have a pool of water.
What is the fewest number of steps it takes to come up with exactly 6 liters of water?
(A step is defined as pouring water into a jug. For instance, filling the four-liter jug and emptying it into the nine-liter jug would be two steps.)
Solution:
Six.
1. Fill the nine-liter jug from the pool.
2. Fill the four-liter jug from the nine-liter one, leaving five liters in the larger jug.
3. Empty the four-liter jug, and empty more water into the nine-liter one -- this will leave one liter of water in the larger jug.
4. Empty the four-liter jug again, and pour the one liter remaining into it.
5. Fill the nine-liter jug from the pool.
6. Fill the four-liter jug, which already has one liter in it, from the larger jug -- this would take only three liters, leaving exactly six liters in the nine-liter jug.
Today's brain teaser courtesy of Braingle.com.
