Hint to Riddle #22: The 3 & 5 Litre Die Hard Water Puzzle
This puzzle gets a surge of hits a few times a year and I know that somewhere Die Hard: With a Vengeance has been on TV.
The puzzle is pure in the sense that it doesn't rely on guessing what a half-full can looks like or balancing anything. It can be done exactly by simply filling and pouring away.
This puzzle has two completely different solutions both equally valid. In order to get 4 litres in the 5 litre can we are either...
...going to have to get one litre in to the 5 litre can so we can top it up with a full 3 litres. And know we have 4 litres.
...get 2 litres in to the 3 litre can so we can fill the 5 litre can from the tap and pour away exactly 1 litre into the 3 litre can.
If you like that is the step before the end.
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