inverse-permutation ( seq -- permutation )

Vocabulary

math.combinatorics

Inputs

seq	a sequence

Outputs

permutation

a sequence

Word description

Outputs a sequence of indices representing the lexicographical permutation of seq.

Notes

All items in seq must be comparable by <=>.

Examples

USING: math.combinatorics prettyprint ; "dcba" inverse-permutation .
{ 3 2 1 0 }

USING: math.combinatorics prettyprint ; { 12 56 34 78 } inverse-permutation .
{ 0 2 1 3 }

Definition

USING: assocs sorting ;

IN: math.combinatorics

: inverse-permutation ( seq -- permutation )
    <enumerated> sort-values keys ;