day 07 part 1 fortran

1 files changed, 57 insertions, 0 deletions

diff --git a/2024/day_07.f90 b/2024/day_07.f90
new file mode 100644
index 0000000..07657ae
--- /dev/null
+++ b/2024/day_07.f90
@@ -0,0 +1,57 @@
+module day_07_utils
+   use iso_fortran_env, only: int64
+   implicit none
+contains
+   recursive function test_values(arr, target, next_idx, current_value) result(pass)
+      implicit none
+      integer(kind=int64), intent(in) :: target, current_value, arr(:)
+      integer, intent(in) :: next_idx
+      logical :: pass
+      if(next_idx > size(arr)) then
+         pass = current_value == target
+         return
+      end if
+      pass = test_values(arr, target, next_idx + 1, current_value + arr(next_idx)) .or. &
+         test_values(arr, target, next_idx + 1, current_value * arr(next_idx))
+   end function test_values
+   logical function is_calibrated(arr, target)
+      implicit none
+      integer(kind=int64), intent(in) :: target, arr(:)
+      is_calibrated = test_values(arr, target, 2, arr(1))
+   end function is_calibrated
+end module day_07_utils
+program day_07
+   use iso_fortran_env, only: int64
+   use day_07_utils
+   implicit none
+   integer(kind=int64) :: test_number, res
+   integer(kind=int64), allocatable:: work(:)
+   integer :: io, ios, idx, i, ct
+   character(len=200) :: line, work_line
+   logical :: pass
+   res = 0
+   open(newunit=io, file='./day_07_input.txt', status='old', action='read')
+   do
+      read(io, '(a)', iostat=ios) line
+      if (ios /= 0) exit
+      idx = index(line, ':')
+      if (idx > 0) then
+         read(line(1:idx-1), *) test_number
+         ct = 0
+         work_line = trim(line(idx+1:len(trim(line))))
+         do i = 1 , len(trim(work_line))
+            if(work_line(i:i) == ' ') then
+               ct = ct + 1
+            end if
+         end do
+         allocate(work(ct))
+         read(work_line, *) work(:)
+      end if
+      pass = is_calibrated(work, test_number)
+      if(pass) then
+         res = res + test_number
+      end if
+      deallocate(work)
+   end do
+   print*, "Result: ", res
+end program day_07