commit 1e697e801c23dbba77092f2a2200d11bace8bccb · treybastian.com/advent-of-code

+112
2024/day_05.f90
···

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       module day_05_utils

     

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       contains

     

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          subroutine append_to_integer_array(arr, val)

     

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             integer, allocatable, intent(inout) :: arr(:)

     

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             integer, intent(in) :: val

     

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             integer, allocatable :: temp(:)

     

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             if(.not. allocated(arr)) then

     

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                ERROR STOP 'Array not allocated'

     

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             end if

     

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             allocate(temp(size(arr) + 1))

     

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             temp(1:size(arr)) = arr

     

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             temp(size(arr) + 1) = val

     

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             call move_alloc(temp, arr)

     

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          end subroutine append_to_integer_array

     

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       end module day_05_utils

     

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       program day_05

     

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          use day_05_utils

     

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          implicit none

     

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          integer :: io, ios, idx, a, b, ct, i, j, res

     

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          integer, allocatable :: left(:), right(:), print_list(:), work(:)

     

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          character(len=100) ::line

     

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          logical :: found

     

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          open(newunit=io, file='./day_05_input.txt', status='old', action='read')

     

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          res = 0

     

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          do

     

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             read(io, '(a)', iostat=ios) line

     

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             if(ios /= 0) exit !eof

     

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             idx = index(line, '|')

     

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             if(idx > 0) then ! rules

     

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                read(line(1:idx-1), *) a

     

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                read(line(idx+1:), *) b

     

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                if(.not. allocated(left)) then

     

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                   allocate(left(1))

     

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                   left(1) = a

     

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                else

     

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                   call append_to_integer_array(left, a)

     

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                end if

     

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                if(.not. allocated(right)) then

     

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                   allocate(right(1))

     

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                   right(1) = b

     

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                else

     

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                   call append_to_integer_array(right, b)

     

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                end if

     

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             end if

     

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             idx = index(line, ',')

     

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             if (idx > 0 ) then ! print_list

     

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                ct = 1

     

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                do i = 1 , len_trim(line)

     

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                   if(line(i:i) == ',') then

     

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                      ct = ct + 1

     

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                   end if

     

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                end do

     

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                allocate(print_list(ct))

     

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                read(line, *) print_list

     

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                found = .false.

     

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                do i = 1, size(print_list)

     

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                   if(i+1 < size(print_list)) then ! if we can check forward

     

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                      do j = 1, size(right) ! find value in right and save left to work

     

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                         if (print_list(i) == right(j)) then

     

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                            if(.not. allocated(work)) then

     

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                               allocate(work(1))

     

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                               work(1) = left(j)

     

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                            else

     

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                               call append_to_integer_array(work, left(j))

     

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                            end if

     

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                         end if

     

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                      end do

     

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                      do j = 1, size(work)

     

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                         if(any(print_list(i+1:size(print_list)) == work(j))) then

     

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                            found = .true.

     

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                            exit

     

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                         end if

     

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                      end do

     

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                      deallocate(work)

     

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                   end if

     

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                   if(.not. found) then ! if we are still valid lets keep going

     

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                      if(i-1 > 0) then ! if we can check backwards

     

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                         do j = 1, size(left) ! find value in left and save left to work

     

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                            if (print_list(i) == left(j)) then

     

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                               if(.not. allocated(work)) then

     

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                                  allocate(work(1))

     

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                                  work(1) = right(j)

     

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                               else

     

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                                  call append_to_integer_array(work, right(j))

     

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                               end if

     

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                            end if

     

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                         end do

     

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                         do j = 1, size(work)

     

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                            if(any(print_list(1:i-1) == work(j))) then

     

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                               found = .true.

     

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                               exit

     

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                            end if

     

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                         end do

     

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                         deallocate(work)

     

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                      end if

     

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                   else

     

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                      exit

     

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                   end if

     

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                end do

     

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                if (.not. found) then

     

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                   res = res + print_list((size(print_list) + 1)/2)

     

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                end if

     

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                deallocate(print_list)

     

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             end if

     

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          end do

     

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          deallocate(left)

     

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          deallocate(right)

     

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          print*, "Result ", res

     

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       end program day_05