Hey, spoiler alert! Guess you'll need to subscribe to Gene's newspapers to find the solution.
By inspection, I can come up with at least one date closer than that. So, let's think about the *algorithm* to solve the problem in minimal time, rather than the answer. On Mon, Jul 18, 2016 at 12:20 PM, Ken McGinnis <[email protected]> wrote: > How about 3456-01-23 > > The month can only be 01-12 and the day can only be 01-31 so I would start > there since the year can be almost anything. > > > > On 7/17/2016 11:11 PM, Joe Yoder wrote: >> >> Here is a simple brute force approach with the same count >> >> m.cnt = 0 >> m.Cdate = {^1900-01-01} >> DO WHILE m.Cdate < {^9999-12-31} >> m.str = dtos(m.cdate) >> FOR m.x = 1 TO 8 >> IF OCCURS(SUBSTR(m.str, m.x, 1), m.str) > 1 >> EXIT >> ENDIF >> ENDFOR >> IF m.x = 9 >> m.cnt = m.cnt + 1 >> * WAIT window m.Cdate >> ENDIF >> m.cdate = m.cdate + 1 >> ENDDO >> ?m.cnt >> >> It takes a little over 6 seconds on my machine so it's not faster - just >> simpler. >> >> Joe >> >> >> On Sun, Jul 17, 2016 at 9:06 PM, Darren <[email protected]> wrote: >> >>> This will give you all the dates that have a unique set of digits 1900 to >>> 9999 - probably more efficient ways to do it but this runs sub second on >>> my >>> machine and spits out 44,640 values. Have not done any testing or >>> checking >>> but it'll give you at least an idea. >>> >>> CREATE CURSOR w_dates (uniquedate D) >>> >>> FOR lnYear = 1900 TO 9999 >>> >>> STORE 0 TO lnCheck >>> STORE .F. TO llDuplicate >>> >>> *- Check the year part for duplicate number usage >>> STORE STR(m.lnYear, 4) TO lcYear >>> FOR n = 1 TO 4 >>> >>> STORE VAL(SUBSTR(m.lcYear, n, 1)) TO lnVal >>> >>> IF BITTEST(m.lnCheck, m.lnVal) >>> STORE .T. TO llDuplicate >>> EXIT >>> ELSE >>> lnCheck = BITSET(m.lnCheck, m.lnVal) >>> ENDIF >>> >>> ENDFOR >>> >>> IF m.llDuplicate >>> LOOP >>> ENDIF >>> >>> STORE m.lnCheck TO lnCheckYr >>> >>> *------------------------------------------- >>> *- Process Months >>> *------------------------------------------- >>> FOR lnMth = 1 TO 12 >>> >>> *- Check the mth + year part for duplicate number usage >>> STORE .F. TO llDuplicate >>> >>> STORE PADL(m.lnMth, 2, "0") TO lcMth >>> FOR n = 1 TO 2 >>> >>> STORE VAL(SUBSTR(m.lcMth, n, 1)) TO lnVal >>> >>> IF BITTEST(m.lnCheck, m.lnVal) >>> STORE .T. TO llDuplicate >>> EXIT >>> ELSE >>> lnCheck = BITSET(m.lnCheck, m.lnVal) >>> ENDIF >>> >>> ENDFOR >>> >>> IF m.llDuplicate >>> >>> STORE m.lnCheckYr TO lnCheck && Restore baseline to the year >>> value >>> LOOP >>> >>> ENDIF >>> >>> STORE m.lnCheck TO lnCheckYrMth >>> >>> *------------------------------------------- >>> *- Process Days >>> *------------------------------------------- >>> >>> *- How many days in the month ? >>> lnDays = ICASE(; >>> INLIST(m.lnMth, 1, 3, 5, 7, 8, 10, 12), 31, ; >>> m.lnMth = 2, 28, ; >>> 30) >>> >>> *- Is this a leap Year ? >>> IF m.lnMth = 2 AND MOD(m.lnYear, 4) = 0 AND IIF(MOD(m.lnYear, 100) = >>> 0, >>> IIF(MOD(m.lnYear, 400) = 0, .T., .F.), .T.) >>> STORE 29 TO lnDays >>> ENDIF >>> >>> FOR lnDay = 1 to m.lnDays >>> >>> *- Check the mth + year + day parts for duplicate number usage >>> STORE .F. TO llDuplicate >>> >>> STORE PADL(m.lnDay, 2, "0") TO lcDay >>> FOR n = 1 TO 2 >>> >>> STORE VAL(SUBSTR(m.lcDay, n, 1)) TO lnVal >>> >>> IF BITTEST(m.lnCheck, m.lnVal) >>> STORE .T. TO llDuplicate >>> EXIT >>> ELSE >>> lnCheck = BITSET(m.lnCheck, m.lnVal) >>> ENDIF >>> >>> ENDFOR >>> >>> IF NOT m.llDuplicate >>> >>> INSERT INTO w_dates (; >>> uniquedate) ; >>> VALUES (; >>> DATE(m.lnYear, m.lnMth, m.lnDay)) >>> >>> ENDIF >>> >>> STORE m.lnCheckYrMth TO lnCheck && Restore baseline to the year + >>> month value - check next day in month. >>> >>> ENDFOR >>> >>> STORE m.lnCheckYr TO lnCheck && Check Next Mth in Year >>> >>> ENDFOR >>> >>> ENDFOR >>> >>> -----Original Message----- >>> From: ProfoxTech [mailto:[email protected]] On Behalf Of Gene >>> Wirchenko >>> Sent: Monday, 18 July 2016 2:29 AM >>> To: [email protected] >>> Subject: Checking for All-Different Characters >>> >>> 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 >>> >>> [excessive quoting removed by server] _______________________________________________ Post Messages to: [email protected] Subscription Maintenance: http://mail.leafe.com/mailman/listinfo/profox OT-free version of this list: http://mail.leafe.com/mailman/listinfo/profoxtech Searchable Archive: http://leafe.com/archives/search/profox This message: http://leafe.com/archives/byMID/profox/CACW6n4t0dbH07fkrBnYy2ooVZLv9A=sjhc4cjf57f84eypc...@mail.gmail.com ** All postings, unless explicitly stated otherwise, are the opinions of the author, and do not constitute legal or medical advice. This statement is added to the messages for those lawyers who are too stupid to see the obvious.
