AkzhanAbdulinFindIndex.pm

package AkzhanAbdulinFindIndex;

use warnings;
use strict;

use List::BinarySearch qw( binsearch_pos );
 
sub new {
  my ( $class ) = @_;
  return bless 1, $class;
}

sub find {
  my ( $what, $sorted_list ) = @_;
  return  undef  unless $what && $sorted_list && scalar(@$sorted_list);
  return $sorted_list->[0]  if scalar(@$sorted_list) == 1;
  my $count = 0;
  my $pos = binsearch_pos { $count ++; $a <=> $b } $what, @$sorted_list;
  return (0, $count )  if $pos == 0;
  return ( $pos - 1, $count )  if $pos == scalar(@$sorted_list);
  my ( $diff_before, $diff_after ) = ( $what - $sorted_list->[$pos - 1], $sorted_list->[$pos] - $what );
  return ( $pos - 1, $count)  if $diff_before <= $diff_after;
  return ( $pos, $count);
}

1;