day 3 part 1

03a.lisp

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+(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"))

03example.txt

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+987654321111111
+811111111111119
+234234234234278
+818181911112111