Hello:
I write a logic/math puzzle each week. They appear in my blog
(http://genew.ca/) and two local newspapers.
Here is the latest problem:
"Consider a date in YYYY-MM-DD format. What is the next date
where all eight digits will be different?"
I solved this by hand. I decided to verify my solution with a
program. I often cook up something in GW-BASIC, but since VFP has
date functions, I decided to go with it.
It was very easy to set up the framework of the loop. What
threw me for a loop is how to check that all of the digits are
different. I ended up converting the date to string with dtos() and
then testing the string with a rather ugly-looking condition. Is
there something faster?
***** Start of Code *****
* 16s-16.prg
* Date Puzzle
* Last Modification: 2016-07-17
*
* Consider a date in YYYY-MM-DD format. What is the next date where all
* eight digits will be different?
? "*** Execution begins."
? program()
close all
clear all
set talk off
set exact on
set century on
set date ansi
*
local startdate
startdate=date()
? "Start Date: "+transform(startdate)
local trydate, looping
trydate=startdate
looping=.t.
do while looping
local trydtos
trydtos=dtos(trydate)
if right(trydtos,4)="0101"
? "Working on year "+left(trydtos,4)
endif
if;
iif("0"$trydtos,1,0)+;
iif("1"$trydtos,1,0)+;
iif("2"$trydtos,1,0)+;
iif("3"$trydtos,1,0)+;
iif("4"$trydtos,1,0)+;
iif("5"$trydtos,1,0)+;
iif("6"$trydtos,1,0)+;
iif("7"$trydtos,1,0)+;
iif("8"$trydtos,1,0)+;
iif("9"$trydtos,1,0)#8
trydate=trydate+1
else && solution
looping=.f.
endif
enddo
? "Solution is "+transform(trydate)+"."
*
close all
clear all
? "*** Execution ends."
return
***** End of Code *****
Sincerely,
Gene Wirchenko
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