sub solve(@n --> List:D) { my @m = @n; my @N = @m.deepmap(*.clone),; while +@m.unique > 1 { my @m_ = (^(+@m-1)).map({ @m[$_+1] - @m[$_] }); @N.push(@m_.item); @m = @m_; } for +@N-2 ... 0 -> $i { @N[$i].push( @N[$i].tail + @N[$i+1].tail); @N[$i].unshift(@N[$i].head - @N[$i+1].head); } @N[0].tail, @N[0].head } with [«+»] $*IN.lines.map({ solve(.words) }) { put 'part 1: ', .[0]; put 'part 2: ', .[1]; }