From 62e672cde3445192e1cda54d71d02c13b535d384 Mon Sep 17 00:00:00 2001
From: Trey Bastian <2991824+TreyBastian@users.noreply.github.com>
Date: Tue, 3 Dec 2024 09:42:57 +0000
Subject: day 3 part 1

---
 2024/day_03.f90 | 83 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 83 insertions(+)
 create mode 100644 2024/day_03.f90

(limited to '2024/day_03.f90')

diff --git a/2024/day_03.f90 b/2024/day_03.f90
new file mode 100644
index 0000000..fa4c0b5
--- /dev/null
+++ b/2024/day_03.f90
@@ -0,0 +1,83 @@
+program day_03
+   implicit none
+   integer ::io, ios, a, b, state, res, cmd_state, digit_state
+   character(len=1) :: c
+   character(len=10) :: buffer ! buffer to store the number
+   res = 0
+   open(newunit=io, file='./day_03_input.txt', status='old', action='read', access='stream')
+   state = 0 ! 0 = find command, 1 = find number, 3 = calculate
+   digit_state = 0 ! 0 = find a, 1 = find b
+   cmd_state = 0 ! 0 = find m, 1 = find u, 2 = find l 3 = find (
+   buffer = ''
+   do
+      read(io, iostat=ios) c
+      if (ios /= 0) exit
+      select case(state)
+       case (0) ! find command
+         select case(cmd_state)
+          case (0) ! find m
+            if (c == 'm') then
+               cmd_state = 1
+            else
+               cmd_state = 0
+            end if
+          case (1) ! find u
+            if (c == 'u') then
+               cmd_state = 2
+            else
+               cmd_state = 0
+            end if
+          case(2) ! find l
+            if (c == 'l') then
+               cmd_state = 3
+            else
+               cmd_state = 0
+            end if
+          case(3)   ! find (
+            if (c == '(') then
+               state = 1
+               cmd_state = 0
+            else
+               cmd_state = 0
+            end if
+         end select
+       case (1) ! find digits
+         select case (iachar(c))
+          case (48:57) ! 0-9
+            buffer = trim(buffer) // c
+          case (44) ! ,
+            if (digit_state == 0 .and. len(trim(buffer)) > 0) then
+               read(buffer, *) a
+               print*, 'a: ', a
+               buffer = ''
+               digit_state = 1
+            else
+               state = 0 ! invalid
+               digit_state = 0
+               buffer = ''
+            end if
+          case (41) ! )
+            if(digit_state == 1 .and. len(trim(buffer)) > 0) then
+               read(buffer, *) b
+               print*, 'b: ', b
+               state = 3 ! reset state
+               digit_state = 0
+               buffer = ''
+            else
+               state = 0
+               digit_state = 0
+               buffer = ''
+            end if
+          case default
+            state = 0
+            digit_state = 0
+            buffer = ''
+         end select
+      end select
+      if(state == 3) then
+         res = res + (a * b)
+         state = 0
+      end if
+   end do
+   print*, res
+end program
-- 
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