clojure jherrlin day8

clojure/jherrlin/day8/day8.clj

@@ -0,0 +1,136 @@
+(ns day8
+  (:require [clojure.string :as str]))
+
+(comment
+  (remove-ns 'day8)
+  )
+
+(def test-input
+  "30373
+25512
+65332
+33549
+35390")
+
+(def input
+  (slurp "./input.txt"))
+
+(defn str->int [s]
+  (Integer. s))
+
+(defn parse-input [s]
+  (->> s
+       str/split-lines
+       (mapv (comp (partial mapv (comp str->int str)) seq))))
+
+(defn matrix-size [m]
+  {:width  (->> m first count)
+   :height (->> m count)})
+
+(defn get-x-y [m x y]
+  (get-in m [y x]))
+
+(defn direction-north [m start-x start-y]
+  (map
+   #(get-x-y m start-x %)
+   (range (dec start-y) -1 -1)))
+
+(direction-north (parse-input test-input) 4 4)
+
+(defn direction-south [m start-x start-y]
+  (let [{matrix-height :height} (matrix-size m)]
+    (map
+     #(get-x-y m start-x %)
+     (range (inc start-y) matrix-height))))
+
+(direction-south (parse-input test-input) 0 0)
+
+(defn direction-west [m start-x start-y]
+  (map
+   #(get-x-y m % start-y)
+   (range (dec start-x) -1 -1)))
+
+(direction-west (parse-input test-input) 4 4)
+
+(defn direction-east [m start-x start-y]
+  (let [{matrix-width :width} (matrix-size m)]
+    (map
+     #(get-x-y m % start-y)
+     (range (inc start-x) matrix-width))))
+
+(direction-east (parse-input test-input) 0 0)
+
+(defn highest-tree? [f m start-x start-y]
+  (let [value  (get-x-y m start-x start-y)
+        values (f m start-x start-y)]
+    (if-not (seq values)
+      true
+      (> value (apply max values)))))
+
+(def highest-tree-north? (partial highest-tree? direction-north))
+(highest-tree-north? (parse-input test-input) 2 2)
+
+(def highest-tree-south? (partial highest-tree? direction-south))
+(highest-tree-south? (parse-input test-input) 2 2)
+
+(def highest-tree-east? (partial highest-tree? direction-east))
+(highest-tree-east? (parse-input test-input) 2 2)
+
+(def highest-tree-west? (partial highest-tree? direction-west))
+(highest-tree-west? (parse-input test-input) 2 2)
+
+;; problem 1
+(let [matrix                                      (parse-input input #_test-input)
+      {matrix-width :width matrix-height :height} (matrix-size matrix)]
+  (->> (for [x (range 0 matrix-width) y (range 0 matrix-height)] [x y])
+       (map (fn [[x y]]
+              (->> [highest-tree-north? highest-tree-east? highest-tree-south? highest-tree-west?]
+                   (map (fn [f] (f matrix x y)))
+                   (some true?))))
+       (remove nil?)
+       (count)))
+;; => 1849
+
+
+(defn scenic-score [f m start-x start-y]
+  (let [value (get-x-y m start-x start-y)]
+    (->> (f m start-x start-y)
+         (reduce
+          (fn [{:keys [blocking-tree-found?] :as m} n]
+            (cond
+              blocking-tree-found?
+              (update m :trees conj false)
+              (>= n value)
+              (-> m
+                  (update :trees conj true)
+                  (assoc :blocking-tree-found? true))
+              (< n value)
+              (update m :trees conj true)))
+          {:blocking-tree-found? false
+           :trees                []})
+         :trees
+         (take-while true?)
+         (count))))
+
+(scenic-score direction-north (parse-input test-input) 2 1)   ;; => 1
+(scenic-score direction-west  (parse-input test-input) 2 1)   ;; => 1
+(scenic-score direction-east  (parse-input test-input) 2 1)   ;; => 2
+(scenic-score direction-south (parse-input test-input) 2 1)   ;; => 2
+
+(scenic-score direction-north (parse-input test-input) 2 3)   ;; => 2
+(scenic-score direction-west  (parse-input test-input) 2 3)   ;; => 2
+(scenic-score direction-south (parse-input test-input) 2 3)   ;; => 1
+(scenic-score direction-east  (parse-input test-input) 2 3)   ;; => 2
+
+
+;; problem 2
+(let [matrix                                      (parse-input input #_test-input)
+      {matrix-width :width matrix-height :height} (matrix-size matrix)]
+  (->> (for [x (range 0 matrix-width) y (range 0 matrix-height)] [x y])
+       (map (fn [[x y]]
+              (->> [direction-north direction-west direction-south direction-east]
+                   (map (fn [f]
+                          (scenic-score f matrix x y))))))
+       (map #(apply * %))
+       (apply max)))
+;; => 201600

clojure/jherrlin/day8/input.txt

@@ -0,0 +1,99 @@
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