Apparently, there is a rather uncomplicated way of generating and printing
very large numbers. The 20th Euler problem is supposed to be rather easy.
Of course most Forth will have bignum libraries, but it seems overkill
for this problem.
There is another one where they want the sum of digits of 2^1000.
Ideas?
-marcel
-- ----------------------------------
INCLUDE ../bignum/bignum.frt
(*
( Collection at http://projecteuler.net/index.php?section=problems
)
n! means n * (n - 1) * ... * 3 * 2 * 1
Find the sum of the digits in the number 100!
Example output:
FORTH> euler20
100! = 93,326,215,443,944,152,681,699,238,856,266,700,490,715,968,
264,381,621,468,592,963,895,217,599,993,229,915,608,941,463,976,
156,518,286,253,697,920,827,223,758,251,185,210,916,864,000,000,
000,000,000,000,000,000
The sum of the digits of the number 100! = 648
0.002 seconds elapsed. ok
*)
MAX.DIGITS BIGNUM n!
: Euler20 ( -- )
1 n! V! #101 2 DO n! I VS* LOOP
CR ." 100! = " n! .Vnum
CR ." The sum of the digits of the number 100! = "
0 BEGIN
n! #10 VS/MOD +
n! VS0=
UNTIL
0 D. ;
: .ABOUT CR ." Euler20 -- Finds the sum of the digits in the number 100!"
;
.ABOUT
|
