Talk:100 doors: Difference between revisions
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:The number of times a door is visited is the same as the number of factors of the door's index. Open doors have been visited an odd number of times and only perfect squares have an odd number of factors. This [http://olimu.com/Notes/Monkeys&Doors.htm] explains it.[[User:Drea|Drea]] 16:20, 11 October 2007 (MDT)
::Actually, square numbers have an even number of factors, the odd count comes from the first iteration that opens all doors. --[[User:AlexLehm|AlexLehm]] 22:16, 19 October 2011 (UTC)
::: Integer factors of 5 -> [1, 5], Integer factors of 4 -> [1, 2, 4] (The integer square root gives the list an odd length - other factors are always paired with their matching quotients) [[User:Hout|Hout]] ([[User talk:Hout|talk]]) 07:59, 8 September 2016 (UTC)
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Some of the "solutions" given are incorrect. This problem is also a great example of the "Fence Post" condition often missed by programmers. Look over the solutions and ask yourself if the 100th door is shown to be open or closed.
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