[day09] Part 1 done, does not scale

5 files changed, 67 insertions, 0 deletions

diff --git a/day09/Dockerfile b/day09/Dockerfile
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+++ b/day09/Dockerfile
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+FROM ruby:2.5-slim
+
+WORKDIR /opt
+
+COPY . .
+
+ENTRYPOINT ["./entrypoint"]
diff --git a/day09/Makefile b/day09/Makefile
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index 0000000..df55a83
--- /dev/null
+++ b/day09/Makefile
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+DAY = 09
+
+.PHONY: run clean push
+
+run: build
+	docker run -it --rm aoc2018day$(DAY)
+
+build: part* input
+	docker build -t aoc2018day$(DAY) .
+	touch build
+
+clean:
+	rm -f build
+
+push: build
+	docker tag aoc2018day$(DAY) advent.4574.co.uk/aoc2018day$(DAY)
+	docker push advent.4574.co.uk/aoc2018day$(DAY)
diff --git a/day09/entrypoint b/day09/entrypoint
new file mode 100755
index 0000000..8982d21
--- /dev/null
+++ b/day09/entrypoint
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+#!/bin/bash
+
+if [ -x part1 ] ; then
+	echo -ne "Part 1:\n\t"
+	time ./part1 < input
+fi
+if [ -x part1 -a -x part2 ] ; then
+	echo
+fi
+if [ -x part2 ] ; then
+	echo -ne "Part 2:\n\t"
+	time ./part2 < input
+fi
diff --git a/day09/input b/day09/input
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index 0000000..a8d7ca0
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+++ b/day09/input
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+468 players; last marble is worth 71010 points
diff --git a/day09/part1 b/day09/part1
new file mode 100755
index 0000000..c0c0a5f
--- /dev/null
+++ b/day09/part1
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+#!/usr/bin/env ruby
+
+input = gets.chomp
+input =~ /(\d+) players; last marble is worth (\d+) points/
+num_players = $1.to_i
+num_marbles = $2.to_i
+marbles = [0]
+players = Array.new(num_players, 0)
+current = 0
+player = 0
+
+num_marbles.times do |m|
+  marble = m + 1
+
+  if (marble % 23).zero?
+    players[player] += marble
+    d = (current - 7) % marbles.length
+    players[player] += marbles.delete_at(d)
+    current = d
+  else
+    nm = ((current + 1) % marbles.length) + 1
+    marbles.insert(nm, marble)
+    current = nm
+  end
+
+  player = (player + 1) % num_players
+end
+
+puts players.max