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HHC 2014 Programming Contest
10-05-2014, 08:02 PM (This post was last modified: 10-05-2014 08:13 PM by Werner.)
Post: #35
RE: HHC 2014 Programming Contest
JHM's routine should work if you replace the IFTs by their IF THEN END counterparts:
(untested)

Code:
\<<
  \<< IF DUP2 MOD NOT THEN 
        IF DUP2 > THEN DROP2 -1 2 END 
        END
  \>>
  \-> p
  \<< 1 MAX 2 p EVAL 1 + p EVAL 2 + p EVAL 2 +
      WHILE DUP2 SQ \>= REPEAT
          p EVAL 4 + p EVAL 2 + p EVAL 4 + p EVAL
      2 + p EVAL 4 + p EVAL 6 + p EVAL 2 + p EVAL 6 +
      END DROP 1 >
   \>>
\>>

Remark that I changed the ultimate test to 1 >
This way it will work for 0 and 1, too. I edited my previous post as well.

Or else, my own simple concoction.
Code:
\<<
  1 MAX 2
  IF DUP2 MOD THEN 1 +
  IF DUP2 MOD THEN 2 +
  IF DUP2 MOD THEN 2 + 
  ELSE SWAP END
  ELSE SWAP END
  ELSE SWAP END
  WHILE DUP2 SQ \>= REPEAT
    IF DUP2 MOD THEN 4 +
    IF DUP2 MOD THEN 2 +
    IF DUP2 MOD THEN 4 +
    IF DUP2 MOD THEN 2 +
    IF DUP2 MOD THEN 4 +
    IF DUP2 MOD THEN 6 +
    IF DUP2 MOD THEN 2 +
    IF DUP2 MOD THEN 6 +
    ELSE SWAP END
    ELSE SWAP END
    ELSE SWAP END
    ELSE SWAP END
    ELSE SWAP END
    ELSE SWAP END
    ELSE SWAP END
    ELSE SWAP END
  END
  \>=
\>>

Yet, to speed up the PDP routine, consider the following:
If yyyymm01 is prime and the day before isn't, then we have performed a lengthy primality testing for nothing.
What we should have is a routine BOTHPRIME? that tests two numbers for divisibility by ever increasing factors at the same time - If both are prime, that will gain us nothing, but if one or both are not, then we will gain a lot of time. I think.
How many times does it happen that yyyymm01 is prime and the day before isn't?
To be continued..

Werner
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Messages In This Thread
HHC 2014 Programming Contest - Paul Dale - 09-24-2014, 09:13 AM
RE: HHC 2014 Programming Contest - BruceH - 10-02-2014, 09:35 PM
RE: HHC 2014 Programming Contest - Jeff O. - 09-29-2014, 01:41 PM
RE: HHC 2014 Programming Contest - Jeff O. - 09-30-2014, 04:39 PM
RE: HHC 2014 Programming Contest - Jeff O. - 10-06-2014, 05:01 PM
RE: HHC 2014 Programming Contest - Jeff O. - 10-07-2014, 12:26 PM
RE: HHC 2014 Programming Contest - Werner - 10-03-2014, 07:35 AM
RE: HHC 2014 Programming Contest - C.Ret - 10-05-2014, 10:02 AM
RE: HHC 2014 Programming Contest - Werner - 10-05-2014 08:02 PM



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