From 237265b3873eaeb140bc5280a935eddbd430d0ed Mon Sep 17 00:00:00 2001
From: Luke Hubmayer-Werner <mongoose41@gmail.com>
Date: Mon, 5 Dec 2022 22:13:10 +1030
Subject: [PATCH] 2022 Day 4 Clojure

---
 2022/day4.clj | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)
 create mode 100644 2022/day4.clj

diff --git a/2022/day4.clj b/2022/day4.clj
new file mode 100644
index 0000000..a9951b1
--- /dev/null
+++ b/2022/day4.clj
@@ -0,0 +1,21 @@
+(require '[clojure.string :as str])
+(def lines (str/split-lines (slurp "input/4")))
+(def number-regex #"(?:(?<!\d)-)?\d+")
+(defn parse-int [str] (Integer/valueOf str 10))
+(defn get-numbers [line] (map parse-int (re-seq number-regex line)))
+(def numbers (map get-numbers lines))
+(defn range-within [s0 s1 t0 t1]  ;; either range is a subset of the other
+    (or (<= t0 s0 s1 t1)
+        (<= s0 t0 t1 s1)))
+(defn range-overlaps [s0 s1 t0 t1]  ;; any range overlap
+    (or (<= t0 s0 t1)
+        (<= t0 s1 t1)
+        (<= s0 t0 s1)
+        (<= s0 t1 s1)))
+
+;; Part 1 - one set is a subset of the other
+(println (format "Part 1: %d elves have no unique work in their pairing"
+    (count (filter identity (map #(apply range-within %) numbers)))))
+;; Part 2 - any set overlap
+(println (format "Part 2: %d elf pairs have overlapping work in their pairing"
+    (count (filter identity (map #(apply range-overlaps %) numbers)))))