My yearly advent-of-code solutions
treybastian.com
1module sorting
2 ! apparently you need to put the subroutine in a module
3 implicit none
4 contains
5 subroutine sort(arr)
6 !! a little insertion sort KISS
7 !! also yea we have no in built sorting
8 implicit none
9 integer, intent(inout) :: arr(1000)
10 integer :: i, j, key
11 do i = 2, 1000
12 key = arr(i)
13 j = i - 1
14 do while (j > 0 .and. arr(j) > key)
15 arr(j+1) = arr(j)
16 j = j - 1
17 end do
18 arr(j+1) = key
19 end do
20 end subroutine sort
21end module sorting
22
23program day_01
24 use sorting
25 implicit none
26 integer :: io, i, dist, sim, left(1000), right(1000) ! yea we are coding to the input file and not generic
27 open(newunit=io, file='./day_01_input.txt', status='old', action='read')
28
29 do i = 1, 1000
30 read(io, *) left(i), right(i) ! read both values in line
31 end do
32
33 close(10) ! close the file
34
35 call sort(left)
36 call sort(right)
37
38 ! if we dont init these bad things happen on multiple runs
39 dist = 0
40 sim = 0
41
42 do i = 1, 1000
43 dist = dist + abs(left(i) - right(i))
44 sim = sim + left(i) * count(right == left(i))
45 end do
46
47 print*, "distance: ", dist
48 print*, "similarity: ", sim
49end program day_01
50