2023 Day 8 part 2

main
Petra 2023-12-08 19:09:33 +13:00
parent 490a9c7b7e
commit 76d31619cc
3 changed files with 135 additions and 1 deletions

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@ -2,7 +2,7 @@ FC:=gfortran
FFLAGS:=-Wall -Wno-maybe-uninitialized FFLAGS:=-Wall -Wno-maybe-uninitialized
BIN:=./bin BIN:=./bin
SRC:=./src SRC:=./src
BINS:=./bin/day01.bin ./bin/day01b.bin ./bin/day02.bin ./bin/day03.bin ./bin/day04.bin ./bin/day05.bin ./bin/day05b.bin ./bin/day06.bin ./bin/day07.bin ./bin/day07b.bin ./bin/day08.bin BINS:=./bin/day01.bin ./bin/day01b.bin ./bin/day02.bin ./bin/day03.bin ./bin/day04.bin ./bin/day05.bin ./bin/day05b.bin ./bin/day06.bin ./bin/day07.bin ./bin/day07b.bin ./bin/day08.bin ./bin/day08b.bin
all: aoc19 all: aoc19

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@ -0,0 +1,10 @@
LR
11A = (11B, XXX)
11B = (XXX, 11Z)
11Z = (11B, XXX)
22A = (22B, XXX)
22B = (22C, 22C)
22C = (22Z, 22Z)
22Z = (22B, 22B)
XXX = (XXX, XXX)

124
2023/src/day08b.f90 100644
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@ -0,0 +1,124 @@
program day8b
implicit none
integer, parameter :: max_chars = 400
integer, parameter :: max_nodes = 1000
integer, parameter :: max_iter = 100000
character(200) :: fname
character(max_chars) :: fline
integer :: n_arguments
integer :: istat
character(max_chars) :: dir_ins
integer :: n_dir_ins
integer :: n_nodes
character(len=3) :: node
character(len=1) :: dir
character(len=3) :: nodes(1:max_nodes), lnodes(1:max_nodes), rnodes(1:max_nodes)
integer :: periods(max_nodes)
integer :: cursors(max_nodes)
integer :: n_cursors
integer :: i, ic, i2, LRcur, i3
logical :: found_z
integer, parameter :: b_kind = selected_int_kind(20)
integer(kind=b_kind) :: p_sum
n_arguments = command_argument_count()
if (n_arguments .eq. 1) then
call get_command_argument(1, fname)
print *, "File: ", trim(fname)
print *
else
print *, "Wrong number of arguments: ", n_arguments
stop
end if
open(10, file=fname)
read(10, "(a)") dir_ins
n_dir_ins = len_trim(dir_ins)
read(10, "(a)") fline
n_nodes = 0
do i=1,max_nodes
read(10, "(a)", iostat=istat) fline
if ((len_trim(fline) .eq. 0) .or. (is_iostat_end(istat))) then
exit
end if
read(fline(1:3), "(a)") nodes(i)
read(fline(8:10), "(a)") lnodes(i)
read(fline(13:15), "(a)") rnodes(i)
n_nodes = n_nodes + 1
end do
close(10)
cursors = -1
n_cursors = 0
do i=1, n_nodes
if (nodes(i)(3:3) .eq. "A") then
n_cursors = n_cursors + 1
cursors(n_cursors) = i
end if
end do
print *, "Number of cursors: ", n_cursors
periods = 0
do i=1,max_iter
LRcur = mod(i-1, n_dir_ins) + 1
dir = dir_ins(LRcur:LRcur)
do ic=1,n_cursors
if (dir .eq. "L") then
node = lnodes(cursors(ic))
else
node = rnodes(cursors(ic))
end if
do i2=1, n_nodes
if (nodes(i2) .eq. node) then
cursors(ic) = i2
exit
end if
end do
end do
found_z = .true.
do ic=1,n_cursors
if (nodes(cursors(ic))(3:3) .ne. "Z") then
found_z = .false.
else if (periods(ic) .eq. 0) then
periods(ic) = i
end if
end do
if (found_z) then
exit
end if
end do
if (found_z) then
print *, "Found nodes ending in Z after ", i, " iterations"
else
print *, "Did not find nodes ending in Z after ", max_iter, " iterations"
print *, "Periods:"
print "(1i9)", periods(1:n_cursors)
p_sum = 1
print *
do ic=1,n_cursors
p_sum = p_sum * periods(ic)
end do
print *, "Potential answer: ", p_sum
do i=1,n_cursors-1
do i2 = i+1,n_cursors
do i3=2,periods(i2)
if (mod(periods(i), i3) .eq. 0 .and. mod(periods(i2), i3) .eq. 0) then
do
periods(i) = periods(i) / i3
if (mod(periods(i), i3) .ne. 0) then
exit
end if
end do
end if
end do
end do
end do
print *, "Factors: "
print "(1i9)", periods(1:n_cursors)
p_sum = 1
print *
do ic=1,n_cursors
p_sum = p_sum * periods(ic)
end do
print *, "Potential answer: ", p_sum
end if
end program day8b