1 files changed, 60 insertions, 0 deletions
diff --git a/aoc2021/Day02.cs b/aoc2021/Day02.cs
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+++ b/aoc2021/Day02.cs
@@ -0,0 +1,60 @@
+namespace aoc2021;
+
+/// <summary>
+/// Day 2: <see href="https://adventofcode.com/2021/day/2"/>
+/// </summary>
+public sealed class Day02 : Day
+{
+    public Day02() : base(2, "Dive!")
+    {
+    }
+
+    public override string Part1()
+    {
+        int horiz = 0, depth = 0;
+        foreach (var line in Input)
+        {
+            var s = line.Split(' ');
+            var x = int.Parse(s[1]);
+            switch (s[0])
+            {
+                case "forward":
+                    horiz += x;
+                    break;
+                case "down":
+                    depth += x;
+                    break;
+                case "up":
+                    depth -= x;
+                    break;
+            }
+        }
+
+        return $"{horiz * depth}";
+    }
+
+    public override string Part2()
+    {
+        int aim = 0, depth = 0, horiz = 0;
+        foreach (var line in Input)
+        {
+            var s = line.Split(' ');
+            var x = int.Parse(s[1]);
+            switch (s[0])
+            {
+                case "forward":
+                    horiz += x;
+                    depth += aim * x;
+                    break;
+                case "down":
+                    aim += x;
+                    break;
+                case "up":
+                    aim -= x;
+                    break;
+            }
+        }
+
+        return $"{horiz * depth}";
+    }
+}