(49g 50g) Fast Pascal's triangle and its relatives

[Thomas Klemm]

(08-20-2018 12:43 AM)Joe Horn Wrote:  Smaller but a tad slower (just thinking of alternative methods for fun):

Code:

\<< 0 + LASTARG SWAP + ADD \>>

Similar idea without using LASTARG:

Code:

\<< 0 OVER + SWAP 0 + ADD \>>

BTW: Both variants work with { 1 } while John Keith's solutions starts working with { 1 1 }.
However they can't use the symmetry and do only half of the work when Pascal's triangle is generated.

Instead we'd have to use two programs say ODD and EVEN that we call alternatively.

ODD

Code:

\<< 0 OVER + REVLIST TAIL REVLIST ADD \>>

EVEN

Code:

\<< 0 OVER + SWAP DUP REVLIST HEAD + ADD \>>

Examples:

{ 1 }
ODD
{ 1 }
EVEN
{ 1 2 }
ODD
{ 1 3 }
EVEN
{ 1 4 6 }
ODD
{ 1 5 10 }
EVEN
{ 1 6 15 20 }
ODD
{ 1 7 21 35 }
…

Cheers
Thomas