day 1 done

1 files changed, 50 insertions, 0 deletions

diff --git a/2024/day_01.f90 b/2024/day_01.f90
new file mode 100644
index 0000000..ac4faf1
--- /dev/null
+++ b/2024/day_01.f90
@@ -0,0 +1,50 @@
+module sorting 
+  ! apparently you need to put the subroutine in a module
+  implicit none
+  contains 
+  subroutine sort(arr)
+      !! a little insertion sort KISS
+      !! also yea we have no in built sorting
+    implicit none
+    integer, intent(inout) :: arr(1000)
+    integer :: i, j, key
+    do i = 2, 1000 
+      key = arr(i)
+      j = i - 1
+      do while (j > 0 .and. arr(j) > key)
+        arr(j+1) = arr(j)
+        j = j - 1
+      end do
+      arr(j+1) = key
+    end do
+  end subroutine sort
+end module sorting
+
+program day_01
+  use sorting
+  implicit none
+  integer :: io, i, dist, sim, left(1000), right(1000) ! yea we are coding to the input file and not generic
+  open(newunit=io, file='./day_01_input.txt', status='old', action='read')
+
+  do i = 1, 1000
+    read(io, *) left(i), right(i) ! read both values in line
+  end do
+
+  close(10) ! close the file
+
+  call sort(left)
+  call sort(right)
+
+  ! if we dont init these bad things happen on multiple runs
+  dist = 0 
+  sim = 0
+
+  do i = 1, 1000
+   dist = dist + abs(left(i) - right(i)) 
+   sim = sim + left(i) * count(right == left(i)) 
+  end do
+
+    print*, "distance: ", dist
+    print*, "similarity: ", sim
+end program day_01
+