1 files changed, 26 insertions, 0 deletions
diff --git a/year2021/day2/part1.clj b/year2021/day2/part1.clj
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+++ b/year2021/day2/part1.clj
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+; Day 2, part 1
+; Read a list of instructions from stdin:
+;   "down X" increases depth number by X,
+;   "up X" decreases depth by X,
+;   "forward X" increases xpos by X.
+; Print (xpos * depth) after end of data.
+;
+
+(require '[clojure.string :as str])
+
+(println
+  (reduce *
+    (vals
+      (reduce
+        #(case (first %2)
+           "forward" (update %1 :xpos  + (second %2))
+           "up"      (update %1 :depth - (second %2))
+           "down"    (update %1 :depth + (second %2))
+           )
+        {:xpos 0 :depth 0}
+        (->> (slurp "./in")
+             str/split-lines
+             (map #(str/split % #" "))
+             (map #(update % 1 read-string))
+             )))))
+