Initial Commit

.gitignore

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+.vs
+bin
+obj
+

AdventOfCode.sln

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+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.1.31903.286
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "AdventOfCode", "AdventOfCode\AdventOfCode.csproj", "{16AD44AD-7D38-497A-9477-2D09B21EC955}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{16AD44AD-7D38-497A-9477-2D09B21EC955}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{16AD44AD-7D38-497A-9477-2D09B21EC955}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{16AD44AD-7D38-497A-9477-2D09B21EC955}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{16AD44AD-7D38-497A-9477-2D09B21EC955}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {35FF9F65-08BE-4ECF-80C7-3D5F7524ABFB}
+	EndGlobalSection
+EndGlobal

AdventOfCode/2021/Day1.cs

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+namespace AdventOfCode._2021;
+using System.Collections;
+
+public class Day1
+{
+    public void Part1()
+    {
+        var input = File.ReadAllLines("2021/input/day1.txt").AsInt();
+        int previous = input.First();
+        int count = 0;
+        foreach (var i in input)
+        {
+            if (i > previous)
+            {
+                count += 1;
+            }
+
+            previous = i;
+        }
+
+        Console.WriteLine(count);
+    }
+
+    public void Part2()
+    {
+        var input = File.ReadAllLines("2021/input/day1.txt").AsInt().ToList();
+
+        int previous = input[0] + input[1] + input[2];
+        int count = 0;
+        for (int i = 1; i < input.Count; i++)
+        {
+            if (i + 2 > input.Count - 1)
+            {
+                break;
+            }
+
+            int sum = input[i] + input[i + 1] + input[i + 2];
+
+            if (sum > previous)
+            {
+                count += 1;
+            }
+
+            previous = sum;
+        }
+
+        Console.WriteLine(count); // first input isn't counted.
+    }
+}

AdventOfCode/2021/Day2.cs

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+namespace AdventOfCode._2021;
+
+public class Day2
+{
+    public void Part1()
+    {
+        var input = File.ReadAllLines("2021/input/day2.txt");
+
+        int h = 0;
+        int d = 0;
+
+        foreach (var s in input)
+        {
+            var split = s.Split(' ');
+            (string direction, int units) = (split[0], int.Parse(split[1]));
+
+            if (direction is "forward")
+            {
+                h += units;
+            }
+            else if (direction is "down")
+            {
+                d += units;
+            }
+            else
+            {
+                d -= units;
+            }
+        }
+
+        Console.WriteLine(h * d);
+    }
+
+    public void Part2()
+    {
+        var input = File.ReadAllLines("2021/input/day2.txt");
+
+        int h = 0;
+        int d = 0;
+        int aim = 0;
+
+        foreach (var s in input)
+        {
+            var split = s.Split(' ');
+            (char dir, int units) = (split[0][0], int.Parse(split[1]));
+
+            switch (dir)
+            {
+                case 'f':
+                    h += units;
+                    d += aim * units;
+                    break;
+
+                case 'd':
+                    aim += units;
+                    break;
+
+                case 'u':
+                    aim -= units;
+                    break;
+
+                default:
+                    throw new Exception(dir.ToString());
+            }
+        }
+
+        Console.WriteLine(h * d); // first input isn't counted.
+    }
+}

AdventOfCode/AdventOfCode.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net6.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Content Include="2021\Input\*">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
+  </ItemGroup>
+
+</Project>

AdventOfCode/Program.cs

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+using AdventOfCode._2021;
+
+new Day2().Part2();
+
+Console.ReadLine();

AdventOfCode/Utils.cs

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+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace AdventOfCode
+{
+    internal class Utils
+    {
+    }
+
+    public static class Extensions
+    {
+        public static IEnumerable<int> AsInt(this IEnumerable<string> strings)
+        {
+            return strings.Select(x => int.Parse(x));
+        }
+    }
+}