125 lines
3.7 KiB
Fortran
125 lines
3.7 KiB
Fortran
program day8b
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implicit none
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integer, parameter :: max_chars = 400
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integer, parameter :: max_nodes = 1000
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integer, parameter :: max_iter = 100000
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character(200) :: fname
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character(max_chars) :: fline
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integer :: n_arguments
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integer :: istat
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character(max_chars) :: dir_ins
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integer :: n_dir_ins
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integer :: n_nodes
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character(len=3) :: node
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character(len=1) :: dir
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character(len=3) :: nodes(1:max_nodes), lnodes(1:max_nodes), rnodes(1:max_nodes)
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integer :: periods(max_nodes)
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integer :: cursors(max_nodes)
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integer :: n_cursors
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integer :: i, ic, i2, LRcur, i3
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logical :: found_z
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integer, parameter :: b_kind = selected_int_kind(20)
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integer(kind=b_kind) :: p_sum
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n_arguments = command_argument_count()
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if (n_arguments .eq. 1) then
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call get_command_argument(1, fname)
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print *, "File: ", trim(fname)
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print *
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else
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print *, "Wrong number of arguments: ", n_arguments
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stop
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end if
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open(10, file=fname)
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read(10, "(a)") dir_ins
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n_dir_ins = len_trim(dir_ins)
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read(10, "(a)") fline
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n_nodes = 0
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do i=1,max_nodes
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read(10, "(a)", iostat=istat) fline
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if ((len_trim(fline) .eq. 0) .or. (is_iostat_end(istat))) then
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exit
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end if
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read(fline(1:3), "(a)") nodes(i)
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read(fline(8:10), "(a)") lnodes(i)
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read(fline(13:15), "(a)") rnodes(i)
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n_nodes = n_nodes + 1
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end do
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close(10)
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cursors = -1
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n_cursors = 0
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do i=1, n_nodes
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if (nodes(i)(3:3) .eq. "A") then
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n_cursors = n_cursors + 1
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cursors(n_cursors) = i
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end if
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end do
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print *, "Number of cursors: ", n_cursors
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periods = 0
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do i=1,max_iter
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LRcur = mod(i-1, n_dir_ins) + 1
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dir = dir_ins(LRcur:LRcur)
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do ic=1,n_cursors
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if (dir .eq. "L") then
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node = lnodes(cursors(ic))
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else
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node = rnodes(cursors(ic))
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end if
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do i2=1, n_nodes
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if (nodes(i2) .eq. node) then
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cursors(ic) = i2
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exit
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end if
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end do
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end do
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found_z = .true.
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do ic=1,n_cursors
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if (nodes(cursors(ic))(3:3) .ne. "Z") then
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found_z = .false.
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else if (periods(ic) .eq. 0) then
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periods(ic) = i
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end if
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end do
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if (found_z) then
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exit
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end if
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end do
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if (found_z) then
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print *, "Found nodes ending in Z after ", i, " iterations"
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else
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print *, "Did not find nodes ending in Z after ", max_iter, " iterations"
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print *, "Periods:"
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print "(1i9)", periods(1:n_cursors)
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p_sum = 1
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print *
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do ic=1,n_cursors
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p_sum = p_sum * periods(ic)
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end do
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print *, "Potential answer: ", p_sum
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do i=1,n_cursors-1
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do i2 = i+1,n_cursors
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do i3=2,periods(i2)
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if (mod(periods(i), i3) .eq. 0 .and. mod(periods(i2), i3) .eq. 0) then
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do
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periods(i) = periods(i) / i3
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if (mod(periods(i), i3) .ne. 0) then
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exit
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end if
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end do
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end if
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end do
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end do
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end do
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print *, "Factors: "
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print "(1i9)", periods(1:n_cursors)
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p_sum = 1
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print *
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do ic=1,n_cursors
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p_sum = p_sum * periods(ic)
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end do
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print *, "Potential answer: ", p_sum
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end if
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end program day8b
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