day 1 first simple task

trying out the loop and reading of the files

day1.lisp

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+
+(list 1 2 3)
+
+;;; input - one number per line, different intentories separated by empty new line
+;; need to find what - how much does have the intventory with maximal sum
+;; so, do i have a function that takes in one string?
+;; i guess it would be better to read input from the separate file
+
+;; would also probably be better to read file line a time
+(defvar current-sum 0)
+(defvar current-max -1)
+(with-open-file
+    (in "day1-input.txt")
+  (loop
+    for line = (read-line in nil nil)
+    while line
+    ;; (if (eq line = "") (print "got empty line"))
+
+    ;; collect line
+    ;; do (format t "got line ~A~%" line)
+
+;;; yay, this is somewhat what i want
+    ;; if (string-equal line "") do (format t "got empty line ~A~% in if" line)
+    ;; else do (format t "else branch for nonempty line ~A~%" line)
+    if (string-equal line "") do (progn
+                                   ;; current inventory ended,
+                                   ;; check whether it's new max and null accum
+                                   (if (< current-max current-sum) (setq current-max current-sum) )
+                                   (setq current-sum 0))
+      else do (setq current-sum (+ current-sum (parse-integer line)))
+      ))
+current-max                             ; i got a right answer
+
+;; yay, now i can write a stateful function that gets one line at a time
+;;
+;; what i could probably do is have
+;; if clauses directly in the loop
+;; and additional variables defined and updated in the loop as well
+
+(setq my-int (parse-integer "10497"))
+my-int
+
+;; let's wrap this into single function, i suppose
+(defun calc-max-inventory-calories (filename)
+  (setq current-sum 0)
+  (setq current-max -1)
+  (with-open-file
+      (in filename)
+    (loop
+      for line = (read-line in nil nil)
+      while line
+      if (string-equal line "")
+        do (progn
+             ;; current inventory ended,
+             ;; check whether it's new max and null accum
+             (if (< current-max current-sum)
+                 (setq current-max current-sum)
+                 )
+             (setq current-sum 0))
+      else do (setq current-sum (+ current-sum (parse-integer line)))
+      ))
+  current-max)
+
+      ;; (in "day1-input.txt")
+(calc-max-inventory-calories  "day1-input.txt")