This is my first, humble attempt. The clue is that the algorithm is encountered frequently in nature :-) Hope you like it.

$"="";print"@{[&{sub{($i,$j,@_)=(1,1,split//,
'hrP kc eeatenltarohsr u.J');while(@_){for(1..$i)
{@_=(pop,@_)}push@t,shift;($i,$j)=($i+$j,$i)}@t}}]}\n";
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