Problem of the Day #279: Elves, Elves, Everywhere!December 23, 2011

Posted by Saketh in : potd , trackback

Sohail and Kevin are playing with some elves. They take turns presenting one coin to any elf that is still awake. Each elf will accept a total of $5$ coins before dispensing a present and going to sleep.

If there are $2011$ elves present, and Sohail gets to go first, how many presents is he guaranteed to win? Both Sohail and Kevin play optimally.