1 files changed, 59 insertions, 0 deletions
diff --git a/2020/1/run.cs b/2020/1/run.cs
new file mode 100644
index 0000000..fb2f6ae
--- /dev/null
+++ b/2020/1/run.cs
@@ -0,0 +1,59 @@
+using System;
+using System.IO;
+using System.Linq;
+
+namespace AOC
+{
+    internal class Run
+    {
+        private static int[] Double(int[] arr, int low, int result)
+        {
+            int high = arr.Length - 1;
+
+            int sum = arr[low] + arr[high];
+            while (low < high && sum != result)
+            {
+                if (sum < result)
+                    low++;
+                else
+                    high--;
+
+                sum = arr[low] + arr[high];
+            }
+
+            if (low == high)
+            {
+                return new[] {0, 0};
+            }
+
+            return new[] {arr[low], arr[high]};
+        }
+
+        private static int[] Triple(int[] arr, int result)
+        {
+            for (int i = 0; i < arr.Length; i++)
+            {
+                int remainder = result - arr[i];
+                int[] d = Double(arr, i, remainder);
+                if (d.Sum() != 0)
+                {
+                    return new[] {arr[i], d[0], d[1]};
+                }
+            }
+
+            return new[] {0, 0};
+        }
+
+        public static void Main(string[] args)
+        {
+            string text = File.ReadAllText("input");
+            string[] numsStr = text.Split('\n');
+            numsStr[numsStr.Length - 1] = "2020"; // Some weird newline character ig
+            int[] nums = Array.ConvertAll(numsStr, int.Parse).OrderBy(i => i).ToArray();
+            int[] d = Double(nums, 0, 2020);
+            int[] t = Triple(nums, 2020);
+            Console.WriteLine(d[0] * d[1]);
+            Console.WriteLine(t[0] * t[1] * t[2]);
+        }
+    }
+}