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Statistic identifier: St001569

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Collection: Permutations

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Description: The maximal modular displacement of a permutation.

This is $\max_{1\leq i \leq n} \left(\min(\pi(i)-i\pmod n, i-\pi(i)\pmod n)\right)$ for a permutation $\pi$ of $\{1,\dots,n\}$.

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References: [1]   lemon314 Permutations with bounded displacement on a circle [[MathOverflow:366137]]

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Code:
def statistic(pi):
    n = len(pi)
    return max(min((e-1-i)%n,(i-e+1)%n) for i,e in enumerate(pi))

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Statistic values:

[1,2]       => 0
[2,1]       => 1
[1,2,3]     => 0
[1,3,2]     => 1
[2,1,3]     => 1
[2,3,1]     => 1
[3,1,2]     => 1
[3,2,1]     => 1
[1,2,3,4]   => 0
[1,2,4,3]   => 1
[1,3,2,4]   => 1
[1,3,4,2]   => 2
[1,4,2,3]   => 2
[1,4,3,2]   => 2
[2,1,3,4]   => 1
[2,1,4,3]   => 1
[2,3,1,4]   => 2
[2,3,4,1]   => 1
[2,4,1,3]   => 2
[2,4,3,1]   => 2
[3,1,2,4]   => 2
[3,1,4,2]   => 2
[3,2,1,4]   => 2
[3,2,4,1]   => 2
[3,4,1,2]   => 2
[3,4,2,1]   => 2
[4,1,2,3]   => 1
[4,1,3,2]   => 2
[4,2,1,3]   => 2
[4,2,3,1]   => 1
[4,3,1,2]   => 2
[4,3,2,1]   => 1
[1,2,3,4,5] => 0
[1,2,3,5,4] => 1
[1,2,4,3,5] => 1
[1,2,4,5,3] => 2
[1,2,5,3,4] => 2
[1,2,5,4,3] => 2
[1,3,2,4,5] => 1
[1,3,2,5,4] => 1
[1,3,4,2,5] => 2
[1,3,4,5,2] => 2
[1,3,5,2,4] => 2
[1,3,5,4,2] => 2
[1,4,2,3,5] => 2
[1,4,2,5,3] => 2
[1,4,3,2,5] => 2
[1,4,3,5,2] => 2
[1,4,5,2,3] => 2
[1,4,5,3,2] => 2
[1,5,2,3,4] => 2
[1,5,2,4,3] => 2
[1,5,3,2,4] => 2
[1,5,3,4,2] => 2
[1,5,4,2,3] => 2
[1,5,4,3,2] => 2
[2,1,3,4,5] => 1
[2,1,3,5,4] => 1
[2,1,4,3,5] => 1
[2,1,4,5,3] => 2
[2,1,5,3,4] => 2
[2,1,5,4,3] => 2
[2,3,1,4,5] => 2
[2,3,1,5,4] => 2
[2,3,4,1,5] => 2
[2,3,4,5,1] => 1
[2,3,5,1,4] => 2
[2,3,5,4,1] => 2
[2,4,1,3,5] => 2
[2,4,1,5,3] => 2
[2,4,3,1,5] => 2
[2,4,3,5,1] => 2
[2,4,5,1,3] => 2
[2,4,5,3,1] => 2
[2,5,1,3,4] => 2
[2,5,1,4,3] => 2
[2,5,3,1,4] => 2
[2,5,3,4,1] => 2
[2,5,4,1,3] => 2
[2,5,4,3,1] => 2
[3,1,2,4,5] => 2
[3,1,2,5,4] => 2
[3,1,4,2,5] => 2
[3,1,4,5,2] => 2
[3,1,5,2,4] => 2
[3,1,5,4,2] => 2
[3,2,1,4,5] => 2
[3,2,1,5,4] => 2
[3,2,4,1,5] => 2
[3,2,4,5,1] => 2
[3,2,5,1,4] => 2
[3,2,5,4,1] => 2
[3,4,1,2,5] => 2
[3,4,1,5,2] => 2
[3,4,2,1,5] => 2
[3,4,2,5,1] => 2
[3,4,5,1,2] => 2
[3,4,5,2,1] => 2
[3,5,1,2,4] => 2
[3,5,1,4,2] => 2
[3,5,2,1,4] => 2
[3,5,2,4,1] => 2
[3,5,4,1,2] => 2
[3,5,4,2,1] => 2
[4,1,2,3,5] => 2
[4,1,2,5,3] => 2
[4,1,3,2,5] => 2
[4,1,3,5,2] => 2
[4,1,5,2,3] => 2
[4,1,5,3,2] => 2
[4,2,1,3,5] => 2
[4,2,1,5,3] => 2
[4,2,3,1,5] => 2
[4,2,3,5,1] => 2
[4,2,5,1,3] => 2
[4,2,5,3,1] => 2
[4,3,1,2,5] => 2
[4,3,1,5,2] => 2
[4,3,2,1,5] => 2
[4,3,2,5,1] => 2
[4,3,5,1,2] => 2
[4,3,5,2,1] => 2
[4,5,1,2,3] => 2
[4,5,1,3,2] => 2
[4,5,2,1,3] => 2
[4,5,2,3,1] => 2
[4,5,3,1,2] => 2
[4,5,3,2,1] => 2
[5,1,2,3,4] => 1
[5,1,2,4,3] => 2
[5,1,3,2,4] => 2
[5,1,3,4,2] => 2
[5,1,4,2,3] => 2
[5,1,4,3,2] => 2
[5,2,1,3,4] => 2
[5,2,1,4,3] => 2
[5,2,3,1,4] => 2
[5,2,3,4,1] => 1
[5,2,4,1,3] => 2
[5,2,4,3,1] => 1
[5,3,1,2,4] => 2
[5,3,1,4,2] => 2
[5,3,2,1,4] => 2
[5,3,2,4,1] => 1
[5,3,4,1,2] => 2
[5,3,4,2,1] => 2
[5,4,1,2,3] => 2
[5,4,1,3,2] => 2
[5,4,2,1,3] => 2
[5,4,2,3,1] => 2
[5,4,3,1,2] => 2
[5,4,3,2,1] => 2

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Created: Jul 21, 2020 at 21:37 by Martin Rubey

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Last Updated: Jul 21, 2020 at 21:37 by Martin Rubey