From 3aff1cd302e2c2488daaf4b89b2aa587a2d9e5a9 Mon Sep 17 00:00:00 2001
From: Alan Daniels <alan.daniels10@gmail.com>
Date: Sat, 6 Dec 2025 18:46:23 +1100
Subject: [PATCH] day 3 part 1

---
 03a.lisp      | 23 +++++++++++++++++++++++
 03example.txt |  4 ++++
 2 files changed, 27 insertions(+)
 create mode 100644 03a.lisp
 create mode 100644 03example.txt

diff --git a/03a.lisp b/03a.lisp
new file mode 100644
index 0000000..8add288
--- /dev/null
+++ b/03a.lisp
@@ -0,0 +1,23 @@
+(require :uiop)
+(load (sb-ext:posix-getenv "ASDF"))
+(asdf:load-system 'str)
+
+(defun bank-max-joltage (bank)
+  (let ((batt-len (- (length bank) 1)))
+  (apply #'max
+    (loop for batt-first from 0 to (- batt-len 1)
+      collect (apply #'max
+        (loop for batt-last from (+ batt-first 1) to batt-len
+          collect (let (
+            (first-char (subseq bank batt-first (+ batt-first 1)))
+            (last-char (subseq bank batt-last (+ batt-last 1))))
+            (parse-integer (format nil "~A~A" first-char last-char)))))))))
+(bank-max-joltage "987654321111111")
+
+
+(defun array-total-joltage (bank-list)
+  (reduce #'+
+    (mapcar #'bank-max-joltage bank-list)))
+
+(array-total-joltage (uiop:read-file-lines "03example.txt"))
+(array-total-joltage (uiop:read-file-lines "03data.txt"))
diff --git a/03example.txt b/03example.txt
new file mode 100644
index 0000000..7255fca
--- /dev/null
+++ b/03example.txt
@@ -0,0 +1,4 @@
+987654321111111
+811111111111119
+234234234234278
+818181911112111