HP 49G Programming Challenge: OEIS A014261, Integers with exclusively Odd Digits

[pier4r]

So finally I was able to implement an idea similar to what I wanted to do.

I am happy because (a) I implemented my idea and (b) I heavily used community libraries that are awesome. The drawback is that the idea is very inefficient. It is also true that I wouldn't be able to get to the same level of some solutions already posted. Those are relatively refined compared to my skills.

In particular with DOPERM I did not identify a way to create "ordered permutations" through which I could halt the execution earlier.

Well does not matter, the first objective is to get the answer correct, if possible with a nice way. Then optimizations may be applied.

Ah, 50th number asked (179), 190 seconds.
Also I am not sure it can process some large number, like 8000.

Code:


OEISA014261
  @see www.hpmuseum.org/forum/thread-8928.html
  @in practice we should generate all the positive integers not containing
  @even digits.
  @Those small challenegs are nice because are not overwhelming and still can be
  @approached in many ways.
  
  @listExt of DavidM
  @LSORT from hpcalc
  \<<
    @Input: N
    @Output: Nth number in the sequence.
  
    @Plan
    @ combining digits 1 3 5 7 9 in increasing way.
    
    @so making heavy use of the awesome list library of david.
    @I can just generate tuples and sort them.
    
    { 1 3 5 7 9 } "baseList" DROP
    { } "currentIterBaseList" DROP
    {} "currentIterationList" DROP
    1 "digitsInIteration" DROP
    0 "mthGeneratedNumber" DROP
    0 "skippedNumbers" DROP
    
    \->
    @input
    valueN
    
    @local var
    baseList
    currentIterBaseList
    currentIterationList
    digitsInIteration
    mthGeneratedNumber
    skippedNumbers
    \<<
      IF
        valueN 1 > NOT
      THEN
        0
      ELSE
        WHILE
          valueN 5 digitsInIteration ^
          >
        REPEAT
          'skippedNumbers' 5 digitsInIteration ^ STO+
          'digitsInIteration' 1 STO+
        END

        @generate a source list with enough digits 
        @(small limits of the current version of the list library of davidM)
        @in general to generate 111 we need 3 "1" in the list, so
        baseList digitsInIteration LMRPT 'currentIterBaseList' STO
          @can we use sorted? so we have the numbers generated in order?
          @nu. Generating a list from sorted input list and then removing duplicates
          @does not help. This may be a request for another command similar to DOPERM
        
        @generate all the permutations of the elements, turn them in numbers
        @clear the equal ones
        currentIterBaseList digitsInIteration 
        \<< NL\->I \>> 
        DOPERM
        LDDUP
        :2:LSORT EVAL
        
        @then we pick the right element
        valueN skippedNumbers -
        GET
      END
    \>>
  \>>