Created
June 19, 2013 00:31
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Solving some Project Euler problems to become more familiar with factor. This is pretty old, but I thought it'd be worth stashing here for safekeeping.
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USING: | |
kernel | |
sequences | |
sequences.deep | |
math | |
math.functions | |
math.order | |
math.ranges | |
math.primes | |
math.primes.factors | |
project-euler.common | |
fry | |
; | |
IN: euler | |
: prob3 ( n -- f ) factors last ; | |
: prob7 ( n -- nth ) nth-prime ; | |
: prob10 ( max -- sum ) primes-upto sum ; | |
: prob1 ( n -- n ) | |
1 (a,b] | |
[ | |
[ 3 mod 0 = ] | |
[ 5 mod 0 = ] bi or | |
] filter | |
sum | |
; | |
: fibs-upto ( max -- seq ) | |
'[ dup first2 + _ <= ] | |
{ 2 1 } swap | |
[ dup first2 + prefix ] while | |
; | |
: prob2 ( max -- n ) | |
fibs-upto [ even? ] filter sum | |
; | |
: prob4 ( digits -- max ) | |
10 swap ^ dup 10 / (a,b] | |
dup [ * ] cartesian-map flatten | |
[ palindrome? ] filter | |
0 [ max ] reduce | |
; | |
: prob5 ( max -- n ) | |
1 [a,b] 1 [ lcm ] reduce | |
; | |
: prob6 ( max -- n ) | |
1 [a,b] dup | |
sum 2 ^ swap | |
[ 2 ^ ] map sum - | |
; | |
: prob12 ( max -- n ) | |
1 1 rot '[ dup divisors length _ < ] | |
[ swap 1 + swap over + ] while nip | |
; | |
: prob16 ( pow -- sum ) | |
2 swap ^ number>digits sum | |
; |
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