From 8d43e37df99f280377bed90284d6ac2428334804 Mon Sep 17 00:00:00 2001
From: Clyne Sullivan <clyne@bitgloo.com>
Date: Wed, 30 Nov 2022 19:55:31 -0500
Subject: move 2021 days to folder; update README

---
 year2021/day10/part1.clj    | 22 ++++++++++++++++++++++
 year2021/day10/part2.clj    | 24 ++++++++++++++++++++++++
 year2021/day10/partboth.clj | 34 ++++++++++++++++++++++++++++++++++
 3 files changed, 80 insertions(+)
 create mode 100644 year2021/day10/part1.clj
 create mode 100644 year2021/day10/part2.clj
 create mode 100644 year2021/day10/partboth.clj

(limited to 'year2021/day10')

diff --git a/year2021/day10/part1.clj b/year2021/day10/part1.clj
new file mode 100644
index 0000000..60ed1e6
--- /dev/null
+++ b/year2021/day10/part1.clj
@@ -0,0 +1,22 @@
+(def to-closing {\{ \} \( \) \[ \] \< \>})
+(def to-score {\) 3 \] 57 \} 1197 \> 25137})
+
+(defn check-line [input]
+  (loop [in input open '()]
+    (when-let [c (first in)]
+      (if (some->> (#{\} \) \] \>} c) (not= (first open)))
+        c
+        (recur
+          (rest in)
+          (if-let [op (to-closing c)]
+            (conj open op)
+            (rest open)
+            ))))))
+
+(->> (slurp "./in")
+     (clojure.string/split-lines)
+     (map (comp to-score check-line vec))
+     (filter some?)
+     (apply +)
+     (println))
+
diff --git a/year2021/day10/part2.clj b/year2021/day10/part2.clj
new file mode 100644
index 0000000..4dfaf3b
--- /dev/null
+++ b/year2021/day10/part2.clj
@@ -0,0 +1,24 @@
+(def to-closing {\{ \} \( \) \[ \] \< \>})
+(def to-score {\) 1 \] 2 \} 3 \> 4})
+
+(defn check-line [input]
+  (loop [in input open '()]
+    (if-let [c (first in)]
+      (when (or (nil? (#{\} \) \] \>} c)) (= (first open) c))
+        (recur
+          (rest in)
+          (if-let [op (to-closing c)]
+            (conj open op)
+            (rest open))))
+      open
+      )))
+
+(->> (slurp "./in")
+     (clojure.string/split-lines)
+     (map (comp check-line vec))
+     (filter some?)
+     (map (partial reduce #(+ (* 5 %1) (to-score %2)) 0))
+     (sort)
+     (#(nth % (quot (count %) 2)))
+     (println))
+
diff --git a/year2021/day10/partboth.clj b/year2021/day10/partboth.clj
new file mode 100644
index 0000000..78080d9
--- /dev/null
+++ b/year2021/day10/partboth.clj
@@ -0,0 +1,34 @@
+(def to-closing {\{ \} \( \) \[ \] \< \>})
+(def to-score {\) 3 \] 57 \} 1197 \> 25137})
+(def to-score2 {\) 1 \] 2 \} 3 \> 4})
+
+(defn check-line [input]
+  (loop [in input open '()]
+    (if-let [c (first in)]
+      (if (some->> (#{\} \) \] \>} c) (not= (first open)))
+        c
+        (recur
+          (rest in)
+          (if-let [op (to-closing c)]
+            (conj open op)
+            (rest open)
+            )))
+      open
+      )))
+
+(->> (slurp "./in")
+     (clojure.string/split-lines)
+     (map (comp check-line vec))
+     ; check-line returns first invalid character, or list of characters
+     ; necessary to close the line. Work through these through `reduce`
+     ; and build the answers for both parts:
+     (reduce
+       (fn [tots nxt]
+         (if (seq? nxt)
+           (update tots 1 #(conj % (reduce (fn [a b] (+ (* 5 a) (to-score2 b))) 0 nxt)))
+           (update tots 0 #(+ % (to-score nxt)))))
+       [0 '()])
+     ; Get part 2 answer from the list of scores:
+     (#(update % 1 (fn [ns] (nth ns (quot (count ns) 2)))))
+     (println))
+
-- 
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