Project Euler is a website dedicated to computational problems intended to be solved with computer programs.
At the time of this writing, it includes over 400 problems, with a new one added every week.
Problems are of varying difficulty but each is solvable in less than a minute using an efficient algorithm on a modestly powered computer.
I have already solved some of the problem, mainly using J (a language in the APL family) or Python.
Last year I learned ABAP and now, to test my skill with it, I decide to solve some of the Project Euler problem using ABAP.
To be able to execute ABAP programs, I have installed a SAP NetWeaver Trial Version ABAP (Windows) under VirtualBox.
The problem 3 (Largest prime factor) is:
The prime factors of 13195 are 5, 7, 13 and 29.
What is the largest prime factor of the number 600851475143 ?
J has a primitive to compute the factors of an integer. So in J the solution is a one-line:
>./ q: 600851475143 NB. max of factors
In Python 3, using a simple algorithm of trial division to compute the factors:
from math import sqrt
def factors( n ) :
ret = [ 1 ]
while n % 2 == 0 :
n //= 2
ret.append( 2 )
lim = int( sqrt( n ) )
i = 3
while i <= lim :
while n % i == 0 :
ret.append( i )
n //= i
lim = int( sqrt( n ) )
i += 2
if n > 1 :
ret.append( n )
return ret
if __name__ == '__main__':
print( "The solution is %d" % factors( 600851475143 )[-1] )
With this problem I started to implement some utility functions and some types in ABAP.
The first of the function is ZMLA_EULER=>FACTORS (see below, after the report ZMLA_EULERO_003) that take an integer as input and produce a list of integer.
Using ZMLA_EULER=>FACTORS we can solve the problem as follow:
REPORT ZMLA_EULERO_003.
FIELD-SYMBOLS: <sol> TYPE ZMLA_EULER=>enumber.
DATA: n TYPE ZMLA_EULER=>enumber VALUE 600851475143,
lst TYPE ZMLA_EULER=>listof_enumber,
sol TYPE i,
s TYPE string.
CALL METHOD ZMLA_EULER=>FACTORS
EXPORTING
N = N
IMPORTING
ORET = lst.
READ TABLE lst ASSIGNING <sol> INDEX lines( lst ).
sol = <sol>.
WRITE / |The solution is { sol ZERO = NO }|.
#### ZMLA_EULER class source code ####
class ZMLA_EULER definition
public
create public .
public section.
types:
enumber TYPE N LENGTH 60 .
types:
listof_enumber TYPE TABLE OF enumber .
class-methods FACTORS
importing
value(N) type ENUMBER
exporting
value(ORET) type listof_enumber .
protected section.
private section.
ENDCLASS.
CLASS ZMLA_EULER IMPLEMENTATION.
* <SIGNATURE>-----------------------------------------------------------------------+
* | Static Public Method ZMLA_EULER=>FACTORS
* +---------------------------------------------------------------------------------+
* | [--->] N TYPE ENUMBER
* | [<---] ORET TYPE LISTOF_ENUMBER
* +----------------------------------------------------------------------</SIGNATURE>
method FACTORS.
CLEAR oret.
APPEND 1 to oret.
WHILE n mod 2 = 0.
n = n / 2.
APPEND 2 to oret.
ENDWHILE.
DATA: lim type enumber,
i type enumber.
lim = sqrt( n ).
i = 3.
WHILE i <= lim.
WHILE n mod i = 0.
APPEND i to oret.
n = n / i.
lim = sqrt( n ).
ENDWHILE.
i = i + 2.
ENDWHILE.
IF n > 1.
APPEND n to oret.
ENDIF.
endmethod.
ENDCLASS.
