Day 10 + small perf checks

2020-12-10 15:05:09 -06:00
parent 921c59ffca
commit 78e2ce126d
5 changed files with 182 additions and 0 deletions
--- a/Q10.cs
+++ b/Q10.cs
@ -0,0 +1,78 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.IO;
+
+namespace _2020
+{
+   class Q10
+   {
+      static List<long> list = new List<long>();
+      static List<long> sortedList = null;
+
+      public static void Go()
+      {
+         var start = DateTime.Now;
+         MakeList();
+         Debug.WriteLine($"Q10 MakeList took {(DateTime.Now - start).TotalMilliseconds}ms");
+         var p1start = DateTime.Now;
+         Part1();
+         Debug.WriteLine($"Q10 part1 took {(DateTime.Now - p1start).TotalMilliseconds}ms");
+         var p2start = DateTime.Now;
+         Part2();
+         Debug.WriteLine($"Q10 part2 took {(DateTime.Now - p2start).TotalMilliseconds}ms");
+
+         Debug.WriteLine($"Q10 took {(DateTime.Now - start).TotalMilliseconds}ms");
+      }
+
+      static void MakeList()
+      {
+         list.Add(0);
+
+         foreach (var line in File.ReadAllLines("10input.txt"))
+         {
+            list.Add(Convert.ToInt64(line));
+         }
+
+         sortedList = new List<long>(list);
+         sortedList.Sort();
+         sortedList.Add(sortedList[^1] + 3);
+      }
+
+      static void Part1()
+      {
+         var diffs = new int[3];
+         for (int i = 1; i < sortedList.Count; i++)
+         {
+            diffs[sortedList[i] - sortedList[i - 1] - 1]++;
+         }
+
+         Debug.WriteLine($"Q10Part1: device joltage={sortedList[^1]}, diffs by 1={diffs[0]}, diffs by 3={diffs[2]}, multiplied={diffs[0] * diffs[2]}");
+      }
+
+      static void Part2()
+      {
+         var pathsToIndices = new List<long>();
+         pathsToIndices.Add(1);
+         for (int i = 1; i < sortedList.Count; i++)
+         {
+            long pathLen = 0;
+            for (int j = i - 1; j >= 0; j--)
+            {
+               if (sortedList[j] + 3 >= sortedList[i])
+               {
+                  pathLen += pathsToIndices[j];
+               }
+               else
+               {
+                  break;
+               }
+            }
+
+            pathsToIndices.Add(pathLen);
+         }
+
+         Debug.WriteLine($"Q10Part2: combinations={pathsToIndices[^1]}");
+      }
+   }
+}