Identifier
- St001005: Permutations ⟶ ℤ
Values
[1,2] => 0
[2,1] => 2
[1,2,3] => 0
[1,3,2] => 2
[2,1,3] => 2
[2,3,1] => 3
[3,1,2] => 3
[3,2,1] => 2
[1,2,3,4] => 0
[1,2,4,3] => 2
[1,3,2,4] => 2
[1,3,4,2] => 3
[1,4,2,3] => 3
[1,4,3,2] => 2
[2,1,3,4] => 2
[2,1,4,3] => 4
[2,3,1,4] => 3
[2,3,4,1] => 4
[2,4,1,3] => 4
[2,4,3,1] => 3
[3,1,2,4] => 3
[3,1,4,2] => 4
[3,2,1,4] => 2
[3,2,4,1] => 3
[3,4,1,2] => 4
[3,4,2,1] => 3
[4,1,2,3] => 4
[4,1,3,2] => 3
[4,2,1,3] => 3
[4,2,3,1] => 2
[4,3,1,2] => 3
[4,3,2,1] => 2
[1,2,3,4,5] => 0
[1,2,3,5,4] => 2
[1,2,4,3,5] => 2
[1,2,4,5,3] => 3
[1,2,5,3,4] => 3
[1,2,5,4,3] => 2
[1,3,2,4,5] => 2
[1,3,2,5,4] => 4
[1,3,4,2,5] => 3
[1,3,4,5,2] => 4
[1,3,5,2,4] => 4
[1,3,5,4,2] => 3
[1,4,2,3,5] => 3
[1,4,2,5,3] => 4
[1,4,3,2,5] => 2
[1,4,3,5,2] => 3
[1,4,5,2,3] => 4
[1,4,5,3,2] => 3
[1,5,2,3,4] => 4
[1,5,2,4,3] => 3
[1,5,3,2,4] => 3
[1,5,3,4,2] => 2
[1,5,4,2,3] => 3
[1,5,4,3,2] => 2
[2,1,3,4,5] => 2
[2,1,3,5,4] => 4
[2,1,4,3,5] => 4
[2,1,4,5,3] => 5
[2,1,5,3,4] => 5
[2,1,5,4,3] => 4
[2,3,1,4,5] => 3
[2,3,1,5,4] => 5
[2,3,4,1,5] => 4
[2,3,4,5,1] => 5
[2,3,5,1,4] => 5
[2,3,5,4,1] => 4
[2,4,1,3,5] => 4
[2,4,1,5,3] => 5
[2,4,3,1,5] => 3
[2,4,3,5,1] => 4
[2,4,5,1,3] => 5
[2,4,5,3,1] => 4
[2,5,1,3,4] => 5
[2,5,1,4,3] => 4
[2,5,3,1,4] => 4
[2,5,3,4,1] => 3
[2,5,4,1,3] => 4
[2,5,4,3,1] => 3
[3,1,2,4,5] => 3
[3,1,2,5,4] => 5
[3,1,4,2,5] => 4
[3,1,4,5,2] => 5
[3,1,5,2,4] => 5
[3,1,5,4,2] => 4
[3,2,1,4,5] => 2
[3,2,1,5,4] => 4
[3,2,4,1,5] => 3
[3,2,4,5,1] => 4
[3,2,5,1,4] => 4
[3,2,5,4,1] => 3
[3,4,1,2,5] => 4
[3,4,1,5,2] => 5
[3,4,2,1,5] => 3
[3,4,2,5,1] => 4
[3,4,5,1,2] => 5
[3,4,5,2,1] => 4
[3,5,1,2,4] => 5
[3,5,1,4,2] => 4
[3,5,2,1,4] => 4
>>> Load all 1200 entries. <<<
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Description
The number of indices for a permutation that are either left-to-right maxima or right-to-left minima but not both.
Code
def rlmin(pi):
n = len(pi)
m = n+1
I = []
for i in range(n):
if pi[n-1-i] < m:
I.append(n-i)
m = pi[n-1-i]
return I
def lrmax(pi):
m = 0
I = []
for i in range(len(pi)):
if pi[i] > m:
I.append(i+1)
m = pi[i]
return I
def statistic(pi):
return len(set(lrmax(pi)).symmetric_difference(rlmin(pi)))
Created
Oct 26, 2017 at 17:51 by Christian Stump
Updated
Jan 13, 2018 at 15:50 by Martin Rubey
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