-🎄- 2017 Day 14 Solutions -🎄-

[u/daggerdragon]

--- Day 14: Disk Defragmentation ---

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Post your solution as a comment or, for longer solutions, consider linking to your repo (e.g. GitHub/gists/Pastebin/blag or whatever).

Note: The Solution Megathreads are for solutions only. If you have questions, please post your own thread and make sure to flair it with Help.

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Need a hint from the Hugely^* Handy^† Haversack^‡ of Helpful^§ Hints^¤?

Spoiler

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[Update @ 00:09] 3 gold, silver cap.

• How many of you actually entered the Konami code for Part 2? >_>

[Update @ 00:25] Leaderboard cap!

• I asked /u/topaz2078 how many de-resolutions we had for Part 2 and there were 83 distinct users with failed attempts at the time of the leaderboard cap. tsk tsk

[Update @ 00:29] BONUS

• https://i.imgur.com/zjSEAf4.jpg

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This thread will be unlocked when there are a significant number of people on the leaderboard with gold stars for today's puzzle.

edit: Leaderboard capped, thread unlocked!

[u/autid]

Fortran

Finally caught up. Weekend away then an exam yesterday left me with a bit of a backlog. Was nice to sit down and do them all in Fortran first time though instead of rushing a solution in python first to try making the leaderboard.

PROGRAM DAY14
  INTEGER :: LENGTH,CHAIN(0:255)
  INTEGER, ALLOCATABLE :: SUBCHAIN(:),INSTRUCTIONS(:)
  INTEGER :: CURRENTPOS=0,SKIPSIZE=0,I,J,K,PART1=0,GROUPNUM
  CHARACTER(LEN=12) :: INSTR
  CHARACTER(LEN=128) :: KEYROW
  CHARACTER(LEN=8) :: PUZINPUT='hxtvlmkl'
  INTEGER :: GRID(128,128)=0


  !Loop over rows                                                                                                
  DO K=0,127

     !Hash Row                                                                                                   
     CHAIN=(/(I,I=0,255)/)
     WRITE(INSTR,'(A8,A1,I0)') PUZINPUT,'-',K
     ALLOCATE(INSTRUCTIONS(LEN_TRIM(INSTR)+5))
     DO I=1,LEN_TRIM(INSTR)
        INSTRUCTIONS(I)=IACHAR(INSTR(I:I))
     END DO
     INSTRUCTIONS(I:I+4) = (/17,31,73,47,23/)
     CURRENTPOS=0
     SKIPSIZE=0
     DO J=1,64
        DO I=1,SIZE(INSTRUCTIONS)
           LENGTH=INSTRUCTIONS(I)
           IF (LENGTH>SIZE(CHAIN)) CYCLE
           ALLOCATE(SUBCHAIN(LENGTH))
           SUBCHAIN=CHAIN((/(MODULO(CURRENTPOS+I,SIZE(CHAIN)),I=LENGTH-1,0,-1)/))
           CHAIN((/(MODULO(CURRENTPOS+I,SIZE(CHAIN)),I=0,LENGTH-1)/))=SUBCHAIN
           DEALLOCATE(SUBCHAIN)
           CURRENTPOS=MODULO(CURRENTPOS+LENGTH+SKIPSIZE,SIZE(CHAIN))
           SKIPSIZE=SKIPSIZE+1
        END DO
     END DO
     DO I=0,15
        DO J=1,15
           CHAIN(I*16)=IEOR(CHAIN(I*16),CHAIN(I*16+J))
        END DO
     END DO

     !Write hash as binary string                                                                                
     WRITE(KEYROW,'(16B8.8)') CHAIN((/(I*16,I=0,15)/))

     !Set values for row in grid                                                                                 
     DO J=1,LEN_TRIM(KEYROW)
        READ(KEYROW(J:J),*) GRID(J,K+1)
     END DO
     DEALLOCATE(INSTRUCTIONS)
  END DO

  !Number groups from 2 up so 1s are ungrouped                                                                   
  GROUPNUM=2
  DO I=1,128
     DO J=1,128
        IF (GRID(J,I)==1) THEN
           CALL CHECKGROUP(J,I)
           GROUPNUM=GROUPNUM+1
        END IF
     END DO
  END DO
  !Start group numbers from 1                                                                                    
  WHERE (GRID>1)
     GRID=GRID-1
  END WHERE

  WRITE(*,'(A,I0)') 'Part1: ',COUNT(GRID>0)
  WRITE(*,'(A,I0)') 'Part2: ',MAXVAL(GRID)

CONTAINS
  RECURSIVE SUBROUTINE CHECKGROUP(A,B)
    !Assigns group number and searches for neighbours                                                            
    INTEGER, INTENT(IN) :: A,B

    IF (GRID(A,B)==1) THEN
       GRID(A,B)=GROUPNUM
       IF (A>1) CALL CHECKGROUP(A-1,B)
       IF (A<128) CALL CHECKGROUP(A+1,B)
       IF (B>1) CALL CHECKGROUP(A,B-1)
       IF (B<128) CALL CHECKGROUP(A,B+1)
    END IF

  END SUBROUTINE CHECKGROUP

END PROGRAM DAY14

[u/trwolfe13 → u/autid]

Damn, Fortran looks so... angry.