Solution to Project Euler problem 25

db4
Aaron Schaefer 2008-01-03 12:21:45 -05:00
parent 0a6975c423
commit 8748979546
3 changed files with 61 additions and 3 deletions

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@ -20,13 +20,13 @@ IN: project-euler.002
! --------
: last2 ( seq -- elt last )
reverse first2 swap ;
2 tail* first2 ;
: fib-up-to ( n -- seq )
: fib-upto ( n -- seq )
{ 0 } 1 [ pick dupd < ] [ add dup last2 + ] [ ] while drop nip ;
: euler002 ( -- answer )
1000000 fib-up-to [ even? ] subset sum ;
1000000 fib-upto [ even? ] subset sum ;
! [ euler002 ] 100 ave-time
! 0 ms run / 0 ms GC ave time - 100 trials

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@ -0,0 +1,57 @@
! Copyright (c) 2007 Aaron Schaefer.
! See http://factorcode.org/license.txt for BSD license.
USING: kernel math math.parser memoize sequences ;
IN: project-euler.025
! http://projecteuler.net/index.php?section=problems&id=25
! DESCRIPTION
! -----------
! The Fibonacci sequence is defined by the recurrence relation:
! Fn = Fn-1 + Fn-2, where F1 = 1 and F2 = 1.
! Hence the first 12 terms will be:
! F1 = 1
! F2 = 1
! F3 = 2
! F4 = 3
! F5 = 5
! F6 = 8
! F7 = 13
! F8 = 21
! F9 = 34
! F10 = 55
! F11 = 89
! F12 = 144
! The 12th term, F12, is the first term to contain three digits.
! What is the first term in the Fibonacci sequence to contain 1000 digits?
! SOLUTION
! --------
MEMO: fib ( m -- n )
dup 1 > [ 1 - dup fib swap 1 - fib + ] when ;
<PRIVATE
: (digit-fib) ( n term -- term )
2dup fib number>string length > [ 1+ (digit-fib) ] [ nip ] if ;
: digit-fib ( n -- term )
1 (digit-fib) ;
PRIVATE>
: euler025 ( -- answer )
1000 digit-fib ;
! [ euler025 ] 10 ave-time
! 5237 ms run / 72 ms GC ave time - 10 trials
MAIN: euler025

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@ -8,6 +8,7 @@ USING: definitions io io.files kernel math.parser sequences vocabs
project-euler.013 project-euler.014 project-euler.015 project-euler.016
project-euler.017 project-euler.018 project-euler.019 project-euler.020
project-euler.021 project-euler.022 project-euler.023 project-euler.024
project-euler.025
project-euler.067 project-euler.134 ;
IN: project-euler