2022 Day 3 Clojure

2022/day3.clj

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+(require '[clojure.string :as str])
+(require '[clojure.set])
+(require '[clojure.zip :as zip])
+
+(def elves (str/split-lines (slurp "input/3")))
+(defn priority [char]
+    (let [
+        c (int char)
+        a (int \a)
+        z (int \z)
+        A (int \A)
+    ]
+    (if (<= a c z)
+        (+ (- c a) 1)
+        (+ (- c A) 27))))
+
+; Part 1
+(defn two-knapsacks [line] (
+    let [
+        half (/ (count line) 2)
+        [knapsack-1 knapsack-2] (map set (split-at half line))
+    ]
+    (priority (first (clojure.set/intersection knapsack-1 knapsack-2)
+))))
+(println (reduce + (map two-knapsacks elves)))
+
+; Part 2
+(defn chunker [sequence num]
+    (if (<= (count sequence) num)
+    [sequence]
+    (let [[head tail] (split-at num sequence)] (lazy-seq (cons head (chunker tail num))))))
+(defn three-elves [lines] (
+    let [
+        sets (map set lines)
+        common (apply clojure.set/intersection sets)
+    ]
+    (priority (first common))))
+(println (reduce + (map three-elves (chunker elves 3))))