Quote:
Originally Posted by psyang
I like the problem, but his explanation on counting the number of loops of length 100 seems wrong.
In the first box, you only have 99 choices (you can't choose itself or you have a loop of 1 which is < 100).
The second box has 98 choices (can't choose itself plus the previous box# or you have a loop of 1 or 2 which is < 100).
etc.
So # of loops of length 100 is 99!
# of unique loops of length 100 is 99!/100.
P(L=100) = (99!/100)/(100!) = 1/10000.
I assume I made a mistake somewhere, but I can't see it. Any ideas?
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The first box (the one with your number) is the first choice in the loop, or it will be the last choice because the 99th box will contain your number. Either way it's 100! no 99!