6 files changed, 215 insertions, 0 deletions
diff --git a/day07/Dockerfile b/day07/Dockerfile
new file mode 100644
index 0000000..5e0a8b7
--- /dev/null
+++ b/day07/Dockerfile
@@ -0,0 +1,7 @@
+FROM ruby:2.5-slim
+
+WORKDIR /opt
+
+COPY . .
+
+ENTRYPOINT ["./entrypoint"]
diff --git a/day07/Makefile b/day07/Makefile
new file mode 100644
index 0000000..6efb4cd
--- /dev/null
+++ b/day07/Makefile
@@ -0,0 +1,17 @@
+DAY = 07
+
+.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/day07/entrypoint b/day07/entrypoint
new file mode 100755
index 0000000..8982d21
--- /dev/null
+++ b/day07/entrypoint
@@ -0,0 +1,13 @@
+#!/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/day07/input b/day07/input
new file mode 100644
index 0000000..c77664d
--- /dev/null
+++ b/day07/input
@@ -0,0 +1,101 @@
+Step M must be finished before step D can begin.
+Step E must be finished before step Z can begin.
+Step F must be finished before step W can begin.
+Step T must be finished before step K can begin.
+Step L must be finished before step Z can begin.
+Step K must be finished before step Q can begin.
+Step H must be finished before step V can begin.
+Step Q must be finished before step P can begin.
+Step B must be finished before step S can begin.
+Step W must be finished before step P can begin.
+Step P must be finished before step R can begin.
+Step A must be finished before step D can begin.
+Step G must be finished before step Z can begin.
+Step I must be finished before step D can begin.
+Step V must be finished before step D can begin.
+Step Z must be finished before step R can begin.
+Step X must be finished before step R can begin.
+Step S must be finished before step U can begin.
+Step J must be finished before step D can begin.
+Step R must be finished before step U can begin.
+Step U must be finished before step Y can begin.
+Step D must be finished before step C can begin.
+Step Y must be finished before step N can begin.
+Step O must be finished before step C can begin.
+Step N must be finished before step C can begin.
+Step Q must be finished before step O can begin.
+Step K must be finished before step Z can begin.
+Step X must be finished before step N can begin.
+Step F must be finished before step I can begin.
+Step F must be finished before step O can begin.
+Step V must be finished before step X can begin.
+Step E must be finished before step N can begin.
+Step V must be finished before step C can begin.
+Step B must be finished before step P can begin.
+Step J must be finished before step U can begin.
+Step D must be finished before step Y can begin.
+Step Z must be finished before step J can begin.
+Step I must be finished before step U can begin.
+Step E must be finished before step O can begin.
+Step X must be finished before step U can begin.
+Step G must be finished before step S can begin.
+Step K must be finished before step X can begin.
+Step G must be finished before step N can begin.
+Step X must be finished before step O can begin.
+Step P must be finished before step G can begin.
+Step L must be finished before step G can begin.
+Step B must be finished before step Y can begin.
+Step W must be finished before step G can begin.
+Step B must be finished before step A can begin.
+Step T must be finished before step S can begin.
+Step J must be finished before step C can begin.
+Step A must be finished before step U can begin.
+Step R must be finished before step D can begin.
+Step U must be finished before step O can begin.
+Step D must be finished before step N can begin.
+Step O must be finished before step N can begin.
+Step Q must be finished before step A can begin.
+Step V must be finished before step J can begin.
+Step W must be finished before step O can begin.
+Step F must be finished before step R can begin.
+Step A must be finished before step X can begin.
+Step H must be finished before step O can begin.
+Step P must be finished before step X can begin.
+Step E must be finished before step Y can begin.
+Step M must be finished before step U can begin.
+Step T must be finished before step C can begin.
+Step A must be finished before step S can begin.
+Step P must be finished before step S can begin.
+Step Q must be finished before step B can begin.
+Step V must be finished before step S can begin.
+Step S must be finished before step Y can begin.
+Step X must be finished before step Y can begin.
+Step H must be finished before step S can begin.
+Step J must be finished before step R can begin.
+Step V must be finished before step U can begin.
+Step X must be finished before step C can begin.
+Step I must be finished before step X can begin.
+Step Y must be finished before step O can begin.
+Step V must be finished before step O can begin.
+Step F must be finished before step L can begin.
+Step T must be finished before step Q can begin.
+Step R must be finished before step O can begin.
+Step E must be finished before step W can begin.
+Step Q must be finished before step Y can begin.
+Step E must be finished before step H can begin.
+Step I must be finished before step R can begin.
+Step B must be finished before step D can begin.
+Step F must be finished before step A can begin.
+Step J must be finished before step Y can begin.
+Step R must be finished before step N can begin.
+Step W must be finished before step A can begin.
+Step D must be finished before step O can begin.
+Step P must be finished before step N can begin.
+Step E must be finished before step Q can begin.
+Step G must be finished before step V can begin.
+Step G must be finished before step I can begin.
+Step X must be finished before step S can begin.
+Step M must be finished before step C can begin.
+Step G must be finished before step X can begin.
+Step T must be finished before step P can begin.
+Step Q must be finished before step Z can begin.
diff --git a/day07/part1 b/day07/part1
new file mode 100755
index 0000000..bd92758
--- /dev/null
+++ b/day07/part1
@@ -0,0 +1,30 @@
+#!/usr/bin/env ruby
+
+input = $stdin.readlines.map do |i|
+  i =~ /Step ([A-Z]) must be finished before step ([A-Z]) can begin./
+  [$2, $1]
+end
+
+steps = input.flatten.uniq.sort
+prereqs = {}
+
+steps.each do |s|
+  prereqs[s] = []
+end
+
+input.each do |i|
+  prereqs[i.first] << i.last
+end
+
+order = []
+
+until prereqs.empty? do
+  next_step = prereqs.select { |k,v| v.empty? }.keys.sort.first
+  order << next_step
+  prereqs.delete(next_step)
+  prereqs.each_key do |k|
+    prereqs[k].delete(next_step)
+  end
+end
+
+puts order.join
diff --git a/day07/part2 b/day07/part2
new file mode 100755
index 0000000..eb71690
--- /dev/null
+++ b/day07/part2
@@ -0,0 +1,47 @@
+#!/usr/bin/env ruby
+
+input = $stdin.readlines.map do |i|
+  i =~ /Step ([A-Z]) must be finished before step ([A-Z]) can begin./
+  [$2, $1]
+end
+
+steps = input.flatten.uniq.sort
+prereqs = {}
+workers = Array.new(5, nil)
+now = 0
+
+steps.each do |s|
+  prereqs[s] = []
+end
+
+input.each do |i|
+  prereqs[i.first] << i.last
+end
+
+until prereqs.empty? && !workers.any? do
+  workers.each_index do |i|
+    next unless workers[i]
+    workers[i][1] -= 1
+    if workers[i][1].zero?
+      ns = workers[i][0]
+      prereqs.each_key do |k|
+        prereqs[k].delete(ns)
+      end
+      workers[i] = nil
+    end
+  end
+
+  next_steps = prereqs.select { |k,v| v.empty? }.keys.sort
+  workers.each_index do |i|
+    unless workers[i] || next_steps.empty?
+      ns = next_steps.shift
+      time = ns.ord - 64 + 60
+      workers[i] = [ns, time]
+      prereqs.delete(ns)
+    end
+  end
+
+  now += 1
+end
+
+puts now - 1