## Wednesday, February 03, 2010

### Canoe Logic

Four adventurers (Alex, Brook, Chris and Dusty) need to cross a river in a small canoe.

The canoe can only carry 100kg.

Alex weighs 90kg, Brook weighs 80kg, Chris weighs 60kg and Dusty weighs 40 kg, and they have 20kg of supplies.

How do they get across?

1. This comment has been removed by the author.

2. I feel like there may be a more efficient way, but this is how it could be done:

Where:
A=Alex
B=Brook
C=Chris
D=Dusty
X=Supplies
()=people on each shore

(ABX) --CD--> ()
(ABX) <-D-- (C)
(A) --CD-> (BX)
(A) <-D-- (BCX)
(D) --A-> (BCX)
(D) <-C-- (ABX)
() --CD-> (ABCDX)

3. Yeah, what Andy said. He beat me to it. Curses! Foiled again.

4. This was my solution, but I really like the graphics you came up with Andy!

Chris and Dusty row across, Dusty returns.
Alex rows over, and Chris returns.
Chris and Dusty row across again, Dusty returns.
Brook rows across with the Supplies, and Chris returns.
Chris and Dusty row across again for the last time.

5. One at a time, with Dusty bringing the supplies on the last run.

6. First, Chris and Dusty row across and Dusty returns. Then, Alex rows over and Chris returns. Once again, Chris and Dusty row over and Dusty returns. This time, Brook rows across with the supplies, and Chris returns. And, for the last time, Chris and Dusty row across. DONE!

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