Re: obj 8-2 topic

Marek Novotny <(E-Mail Removed)> writes:
> On Fri, 21 Feb 2014 22:36:20 +0200, George Mpouras wrote:
>
>> how about finding the answer without IF ?
>>
>>
>> my @array = qw(42 41 42 31 54 420 56 57 46 58 59 60 34 61);
>> my $max = $array[0];
>> $max = (($_ + $max)/2) + (abs($_ - $max)/2) foreach @array[1 ..
>> $#array];
>> print $max
>
> A requirement for the lesson was to use loops and if.
>
> Your solution yielded an answer of 420

Which is correct since a 420 is included in the array. Explanation why
this works: Let the current value be x and m the largest value found so
far. A calculation

(x + m) / 2 + abs(x - m) / 2

is then performed. There are two different cases here

1. x < m

If x < m, then abs(x - m) = m - x hence

(x + m) / 2 + abs(x - m) / 2
= (x + m) / 2 + (m - x) / 2
= (x + m + m - x) / 2
= m

2. x >= m

If x >= m, then abs(x - m) = x - m, hence

(x + m) / 2 + abs(x - m) / 2
= (x + m) / 2 + (x - m) / 2
= (x + m + x - m) / 2
= x

While working this out was moderately entertaining, code isn't supposed
to be worn as a necklace. It is an exectuable description of an
algorithm intended to solve a particular problem and this description
ought to be as simple as possible and not as clever as possible to make
it easy for other people to understand it.