#! perl -slw
use strict;

sub show {
    my ( $ary, $swaps ) = @_;
    printf "%2d swaps => %s\n", $swaps, join ' ', @$ary;
}

sub swapElems {
    my $t = $_[0][ $_[1] ]; $_[0][ $_[1] ] = $_[0][ $_[2] ]; $_[0][ $_[2] ] = $t;
    print "[@{$_[0]}] $_[1] <=> $_[2]"
}

sub do_swaps {
    my( $ary, $x, $y, $swaps ) = @_;
    print "do_swaps: $x .. $y";

    return $swaps if $y == @$ary;
    my $saved_y = $y;

    for( $x .. $y - 1 ) {
        $y = $saved_y if $y == @$ary;

        swapElems( $ary, $x++, $y++ );

        ++$swaps;
    }

    return do_swaps( $ary, $x, $y, $swaps );
}

sub swap {
    my ( $ary, $offset ) = @_;
    my $swaps = do_swaps( $ary, 0, $offset, 0 );
    show( $ary, $swaps );
}


#swap( [ qw( a b c 1 2 3 ) ], 3 );  # aref, offset of Y0
#swap( [ qw( a b c d 1 2 ) ], 4 );
#swap( [ qw( a b c d e 1 ) ], 5 );
swap( [ qw( a b c d e f g h i j 1 2 3 4 5 6 7 8 ) ], 10 );
#swap( [ qw( a b c d e f 1 2 3 ) ], 6 );