commit f84bda29e5ab1145f5842703d9497cce9edf2fc4 · treybastian.com/advent-of-code

+39
2024/day_04_part_2.f90
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       program day_04

     

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          implicit none

     

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          character(len=140) ::  lines(140)

     

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          character(len=1) :: c

     

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          integer :: io, row, col, score, z

     

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          logical :: left_m, right_m

     

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          left_m = .false.

     

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          right_m = .false.

     

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          score = 0

     

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          open(newunit=io, file='./day_04_input.txt', status='old', action='read')

     

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          read(io, '(a)') lines

     

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          do row = 2, size(lines) - 1

     

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             do col = 2, len(lines(row)) - 1

     

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                if (lines(row)(col:col) == 'A') then

     

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                   c = lines(row-1)(col-1:col-1)

     

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                   if (c == 'S' .or. c == 'M') then

     

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                      left_m = c == 'M'

     

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                      c = lines(row-1)(col+1:col+1)

     

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                      if (c == 'S' .or. c == 'M') then

     

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                         right_m = c == 'M'

     

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                         c = lines(row+1)(col-1:col-1)

     

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                         if (right_m .and. c == 'S' .or. (.not. right_m .and. c == 'M')) then

     

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                            c = lines(row+1)(col+1:col+1)

     

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                            if (left_m .and. c == 'S' .or. (.not. left_m .and. c =='M')) then

     

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                               score = score + 1

     

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                            end if

     

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                         end if

     

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                      end if

     

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                   end if

     

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                end if

     

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                left_m = .false.

     

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                right_m = .false.

     

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                c = ''

     

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             end do

     

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          end do

     

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          print*, score

     

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       end program day_04