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A word of length $30$ needs to be formed from the letters $x, y, z$ (repeatable) with the following conditions:

  1. $y$ cannot occur more than once consecutively

  2. $z$ cannot occur more than twice consecutively.

The question is how many such words are possible.

Thanks, Kiran

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    What methods do you know?2011-10-08
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    I dont know how to solve this. I need to know how to approach solving this problem. I know basic permutation/combination techniques.2011-10-08
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    And do you have reason to believe that these techniques are appropriate here?2011-10-08
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    Thats my feeling. I actually need to come with an generalized computer algorithm in the end. I am not looking for answer to the 30 length word question in particular.2011-10-08

4 Answers 4