11511 - Frieze Patterns

All about problems in Volume 115. If there is a thread about your problem, please use it. If not, create one with its number in the subject.

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11511 - Frieze Patterns

Post by wahaha »

i found the period of the numbers is (n+1), but i can not prove it, can anyone help me?
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Re: 11514 - Frieze Patterns

Post by andmej »

I have tried too to prove it without success.

What I did in my code was build the table for the first N+1 rows like this:

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f[i][j] = ( f[i+1][j-1] * f[i-1][j] + 1 ) / f[i][j-1];
So we need to prove that

Code: Select all

f[i][j] = f[i][j-N-1] for all j > N + 1
Does anyone have some idea?
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11511 - Frieze Patterns

Post by yiuyuho »

Problem Link: http://icpcres.ecs.baylor.edu/onlinejud ... 11511.html

Can anyone tell me why the patterns will repeat in exactly n columns?
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