From 896addebb0843d99d9845140eb3b1167bf6e9787 Mon Sep 17 00:00:00 2001
From: Nat Lasseter <user@4574.co.uk>
Date: Sun, 18 Dec 2022 14:34:19 +0000
Subject: Day 18, part 1

---
 day18/part1.rb | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)
 create mode 100644 day18/part1.rb

(limited to 'day18/part1.rb')

diff --git a/day18/part1.rb b/day18/part1.rb
new file mode 100644
index 0000000..dd4ba41
--- /dev/null
+++ b/day18/part1.rb
@@ -0,0 +1,29 @@
+require 'set'
+
+grid = Hash.new
+
+$stdin.readlines.each do |line|
+  x, y, z = line.strip.split(?,).map(&:to_i)
+  grid[x] = Hash.new if grid[x].nil?
+  grid[x][y] = Set.new if grid[x][y].nil?
+  grid[x][y] << z
+end
+
+sa = 0
+
+grid.each do |x, yzs|
+  yzs.each do |y, zs|
+    zs.each do |z|
+      tsa = 6
+      tsa -= 1 if !grid[x-1].nil? && grid[x-1][y]&.include?(z)
+      tsa -= 1 if !grid[x+1].nil? && grid[x+1][y]&.include?(z)
+      tsa -= 1 if grid[x][y-1]&.include?(z)
+      tsa -= 1 if grid[x][y+1]&.include?(z)
+      tsa -= 1 if grid[x][y].include?(z-1)
+      tsa -= 1 if grid[x][y].include?(z+1)
+      sa += tsa
+    end
+  end
+end
+
+puts sa
-- 
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