Reassemble data

#!/usr/bin/perl
use strict;
use warnings;
use utf8;
use open qw|:std :encoding(utf8)|;
use feature 'say';

my $process = {};
my $skip_header = <>;
while (<>) {
  chomp;
  my @line = split /\s*,\s*/;
  $process->{$line[2]} = {} unless defined($process->{$line[2]});
  $process->{$line[2]}->{$line[1]} = $line[0];
}

say join ',', ('処理名', '開始日時', '終了日時');
for my $ps (sort keys %$process) {
  say join ',', ($ps, $process->{$ps}->{開始}, $process->{$ps}->{終了});
}