Hello,

I searched for a solution to my problem on this site already, but for some reason all nodes I found talked about the synetric difference of two arrays, which is not what I want. Maybe the problem has another name?

However, here is the problem. There are two arrays given (array references in that case):

my $before = [qw(1 2 3 4 5 6 7 8 9 10)];
my $after  = [qw(2 3 4 5 1 6 7 8 9 10)];

[download]

The first array always looks the same (ascending numbers from $x to $x + $y). The second array is based on the first array, but one element inside it was moved. In the code example I gave it was element 0 (value 1) that was moved to position 5. The rest of the elements in $after moved up and down automatically.

The operation that was executed on the array could be expressed that way in perl:

my $element = splice(@$after, 0, 1); #remove element 0;
splice(@$after, 4, 0, $element);     #insert element at offset 4

[download]

The question is how to find out which element was moved to which offset, given that you only know the array $before and $after.

TIA, Flo

In reply to Difference between two arrays by rafl

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