From 60ba5e9ab3ab9456663bb4f07fedea31e7ce3a1d Mon Sep 17 00:00:00 2001
From: Jonathan George <Jonathan.George@endjin.com>
Date: Mon, 18 Feb 2019 13:13:31 +0000
Subject: [PATCH] Day 7 part 1

---
 AoC2018.Runner/AoC2018.Runner.csproj |   3 +
 AoC2018.Runner/Input/day07.txt       | 101 +++++++++++++++++++++++++++
 AoC2018.Solutions/Day07/Part01.cs    |  36 ++++++++++
 AoC2018.Tests/AoCTestCases.cs        |   1 +
 4 files changed, 141 insertions(+)
 create mode 100644 AoC2018.Runner/Input/day07.txt
 create mode 100644 AoC2018.Solutions/Day07/Part01.cs

diff --git a/AoC2018.Runner/AoC2018.Runner.csproj b/AoC2018.Runner/AoC2018.Runner.csproj
index ccd34a8..4604660 100644
--- a/AoC2018.Runner/AoC2018.Runner.csproj
+++ b/AoC2018.Runner/AoC2018.Runner.csproj
@@ -28,6 +28,9 @@
     <None Update="Input\day04.txt">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </None>
+    <None Update="Input\day07.txt">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
     <None Update="Input\day06.txt">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </None>
diff --git a/AoC2018.Runner/Input/day07.txt b/AoC2018.Runner/Input/day07.txt
new file mode 100644
index 0000000..4457263
--- /dev/null
+++ b/AoC2018.Runner/Input/day07.txt
@@ -0,0 +1,101 @@
+Step B must be finished before step G can begin.
+Step G must be finished before step J can begin.
+Step J must be finished before step F can begin.
+Step U must be finished before step Z can begin.
+Step C must be finished before step M can begin.
+Step Y must be finished before step I can begin.
+Step Q must be finished before step A can begin.
+Step N must be finished before step L can begin.
+Step O must be finished before step A can begin.
+Step Z must be finished before step T can begin.
+Step I must be finished before step H can begin.
+Step L must be finished before step W can begin.
+Step F must be finished before step W can begin.
+Step T must be finished before step X can begin.
+Step A must be finished before step X can begin.
+Step K must be finished before step X can begin.
+Step S must be finished before step P can begin.
+Step M must be finished before step E can begin.
+Step E must be finished before step W can begin.
+Step D must be finished before step P can begin.
+Step P must be finished before step W can begin.
+Step X must be finished before step H can begin.
+Step V must be finished before step W can begin.
+Step R must be finished before step H can begin.
+Step H must be finished before step W can begin.
+Step N must be finished before step I can begin.
+Step X must be finished before step R can begin.
+Step D must be finished before step V can begin.
+Step V must be finished before step R can begin.
+Step F must be finished before step K can begin.
+Step P must be finished before step R can begin.
+Step P must be finished before step V can begin.
+Step S must be finished before step X can begin.
+Step I must be finished before step S can begin.
+Step J must be finished before step N can begin.
+Step T must be finished before step S can begin.
+Step T must be finished before step R can begin.
+Step K must be finished before step P can begin.
+Step N must be finished before step R can begin.
+Step G must be finished before step T can begin.
+Step I must be finished before step V can begin.
+Step G must be finished before step Q can begin.
+Step D must be finished before step H can begin.
+Step V must be finished before step H can begin.
+Step T must be finished before step K can begin.
+Step T must be finished before step W can begin.
+Step E must be finished before step H can begin.
+Step C must be finished before step R can begin.
+Step L must be finished before step K can begin.
+Step G must be finished before step Y can begin.
+Step Y must be finished before step O can begin.
+Step O must be finished before step E can begin.
+Step U must be finished before step S can begin.
+Step X must be finished before step W can begin.
+Step C must be finished before step D can begin.
+Step E must be finished before step P can begin.
+Step B must be finished before step R can begin.
+Step F 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 M can begin.
+Step B must be finished before step Q can begin.
+Step Q must be finished before step V can begin.
+Step B must be finished before step W can begin.
+Step S must be finished before step H can begin.
+Step P must be finished before step X can begin.
+Step I must be finished before step M can begin.
+Step A must be finished before step S can begin.
+Step M must be finished before step X can begin.
+Step L must be finished before step S can begin.
+Step S must be finished before step W can begin.
+Step L must be finished before step V can begin.
+Step Z must be finished before step X can begin.
+Step M must be finished before step R can begin.
+Step T must be finished before step A can begin.
+Step N must be finished before step V can begin.
+Step M must be finished before step H can begin.
+Step E must be finished before step D can begin.
+Step F must be finished before step V can begin.
+Step B must be finished before step O can begin.
+Step G must be finished before step U can begin.
+Step J must be finished before step C can begin.
+Step G must be finished before step F can begin.
+Step Y must be finished before step M can begin.
+Step F must be finished before step D can begin.
+Step M must be finished before step P can begin.
+Step F must be finished before step T can begin.
+Step G must be finished before step A can begin.
+Step G must be finished before step Z can begin.
+Step K must be finished before step V can begin.
+Step J must be finished before step Z can begin.
+Step O must be finished before step Z can begin.
+Step B must be finished before step E can begin.
+Step Z must be finished before step V can begin.
+Step Q must be finished before step O can begin.
+Step J must be finished before step D can begin.
+Step Y must be finished before step E can begin.
+Step D must be finished before step R can begin.
+Step I must be finished before step F can begin.
+Step M must be finished before step V can begin.
+Step I must be finished before step D can begin.
+Step O must be finished before step P can begin.
\ No newline at end of file
diff --git a/AoC2018.Solutions/Day07/Part01.cs b/AoC2018.Solutions/Day07/Part01.cs
new file mode 100644
index 0000000..563ff31
--- /dev/null
+++ b/AoC2018.Solutions/Day07/Part01.cs
@@ -0,0 +1,36 @@
+namespace AoC2018.Solutions.Day07
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Linq;
+
+    public class Part01 : ISolution
+    {
+        public string Solve(string input)
+        {
+            (string Step, string PreRequisite)[] statements = input.Split(new string[] { Environment.NewLine }, StringSplitOptions.RemoveEmptyEntries).Select(this.ParseStatement).ToArray();
+            string[] allSteps = statements.Select(x => x.Step).Union(statements.Select(x => x.PreRequisite)).Distinct().ToArray();
+            var stepsWithDependencies = allSteps.ToDictionary(x => x, x => statements.Where(s => s.Step == x).Select(s => s.PreRequisite).ToArray());
+
+            var resolvedSteps = new List<string>();
+
+            while (resolvedSteps.Count != allSteps.Length)
+            {
+                resolvedSteps.Add(this.GetNextAvailableStep(stepsWithDependencies, resolvedSteps));
+            }
+
+            return string.Concat(resolvedSteps);
+        }
+
+        private string GetNextAvailableStep(Dictionary<string, string[]> stepsWithDependencies, List<string> resolvedSteps)
+        {
+            return stepsWithDependencies.Where(x => !resolvedSteps.Contains(x.Key)).Where(x => x.Value.All(y => resolvedSteps.Contains(y))).Select(x => x.Key).OrderBy(x => x).First();
+        }
+
+        private (string Step, string PreRequisite) ParseStatement(string statement)
+        {
+            string[] components = statement.Split(' ');
+            return (components[7], components[1]);
+        }
+    }
+}
diff --git a/AoC2018.Tests/AoCTestCases.cs b/AoC2018.Tests/AoCTestCases.cs
index 27c562b..e855027 100644
--- a/AoC2018.Tests/AoCTestCases.cs
+++ b/AoC2018.Tests/AoCTestCases.cs
@@ -30,6 +30,7 @@ public class AoCTestCases
         [TestCase(5, 1, "dabAcCaCBAcCcaDA", "10")]
         [TestCase(5, 2, "dabAcCaCBAcCcaDA", "4")]
         [TestCase(6, 1, "1, 1\r\n1, 6\r\n8, 3\r\n3, 4\r\n5, 5\r\n8, 9", "17")]
+        [TestCase(7, 1, "Step C must be finished before step A can begin.\r\nStep C must be finished before step F can begin.\r\nStep A must be finished before step B can begin.\r\nStep A must be finished before step D can begin.\r\nStep B must be finished before step E can begin.\r\nStep D must be finished before step E can begin.\r\nStep F must be finished before step E can begin.", "CABDFE")]
         public void Tests(int day, int part, string input, string expectedResult)
         {
             ISolution solution = SolutionFactory.GetSolution(day, part);