My approach was slightly different. Since "The first array always looks the same (ascending numbers from $x to $x + $y)", I decided to ignore the first array completely and just focus on what's wrong in the second. Here's my code: 
#!/usr/bin/perl

use strict;
use warnings;

my @array = (1,2,3,6,4,5,7,8,9);
# UPDATED again, numeric sort
my $smallest = (sort {$a <=> $b} @array)[0];
my $stored = shift @array;

# UPDATED per bug report in reply
# if ($stored != $smallest) {
if ($stored != $smallest && $stored + 1 != $array[0]) {
    print "$stored appears to be in the wrong position\n";
    exit;
}

foreach my $i (0 .. $#array) {
    if ($stored != $array[$i] - 1) {
        if ($array[$i] + 1 != $array[$i + 1]) {
            print "$array[$i] appears to be in the wrong position\n";
            last;
        }
    }
    $stored = $array[$i];
}

[download]

---
It's all fine and dandy until someone has to look at the code.

In reply to Re: Difference between two arrays by kwaping
in thread Difference between two arrays by rafl

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