You have an electric car that you want to use to transport some batteries 1,000 miles. You have 3,000 batteries, but your car can only carry 1,000 of them at once. In addition, for each mile that it travels, the car will need to use up one battery in order to power itself.

How many unspent batteries will you be able to transfer to your destination?

The best I can transfer is 500:

1000 to 250 miles, drop 500 and head back. Do this thrice to have 1750 at the 250 mile. (The third time you dont have to go back). Out of this take 1000 to the 500th mile and drop 500 and head back to 250th mile. Pick up the remaining 750 and head back to 500th mile. Now you have 1000 unused at the 500th mile carry all to the finish to have 500 unused.

Posted by chaits on 2002-08-29 12:48:53