forth

gistfile1.factor

." hello world" cr

: hello ." hello world" cr ;

: 3times hello hello hello ;

: ntimes ( n -- ) begin dup 0> while hello 1- repeat drop ;

: sum ( xi n -- sum ) 0 swap begin dup 0> while 1- -rot + swap repeat drop ;

: store-ar ( xi n ^ "name" -- ) create dup , begin dup 0> while 1- swap , repeat drop ;

: sum-ar ( name-of-array -- sum ) 0 swap dup @ begin dup 0> while 1- swap cell+ rot swap dup @ rot + -rot swap repeat 2drop ;

: get-ar-i ( index name-of-array -- i ) swap 1+ cells + @ ;

\ project euler problem1 sum of all number less than 1000
\ that are factors of 3 and 5
: problem1 ( -- sum-35 )
    0
    999
    begin
	dup
	0>
    while
	    dup 3
	    mod
	    0=
	    over 5
	    mod
	    0=
	    or
	    if
		2dup
		+
		-rot
		swap
		drop
	    then
	    1-
    repeat
    drop
;

\ problem 2
\ sum of even numbers of the fibinacci sequence
\ starting with 1 2 (3 5 ...)
: next-fib ( n1 n2 -- n2 n3)
    swap over + ;

: problem2 ( -- sum )
    0
    1
    2
    begin
	dup
	4000000
	<
    while
	    dup
	    2
	    mod
	    0=
	    if
		rot
		over
		+
		-rot
	    then
	    next-fib
    repeat
    2drop
;