This is the first thing I thought, and perhaps the code I'd write...

# ASSERTION: array contains at least 2 elements
@v = (1,2,3,4,5);

$flag = 0;
$first = $v[0];
foreach ( @v[1,] ) { # Starts from second element
    print "Examining $_...\n";
    if ($_ != $first) {
        $flag = 1;
        last;
    }
}
print "All elements are equal" unless $flag;
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Or, using hashes... (Smaller version, but it seems to me THIS is brute force)

@v = (1,2,3,4,5);

map { $set{$_} = 1 } @v;

# Elements are equal, unless set contains more than one element
@k = keys %set;
print "All elements are equal" unless $#k != 1;
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See you
Larsen