feat: solve part 1...summing to zero is bad check when neg nums are present

09/MirageMaintenance/Program.cs

@@ -1,10 +1,35 @@
-namespace MirageMaintenance;
+using System.Diagnostics;
+
+namespace MirageMaintenance;
 
 class Program
 {
   public static async Task<int> Main(string[] args)
   {
-    return await Task.FromResult(0);
+    if (args.Length is 0)
+    {
+      Console.WriteLine("Please provide a path to the input file.");
+      return -1;
+    }
+
+    if (File.Exists(args[0]) is false)
+    {
+      Console.WriteLine("The provided file does not exist.");
+      return -2;
+    }
+
+    var input = await File.ReadAllLinesAsync(args[0]);
+
+    var stopwatch = new Stopwatch();
+    stopwatch.Start();
+
+    var result = OasisReport.Parse(input).CalculateSumOfNextValues();
+
+    stopwatch.Stop();
+
+    Console.WriteLine($"The sum of all next values is {result}. ({stopwatch.ElapsedMilliseconds}ms)");
+
+    return (int)result;
   }
 }
 
@@ -14,6 +39,10 @@ public class OasisReport(
 {
   public List<ValueHistory> ValueHistories { get; init; } = valueHistories;
 
+  public long CalculateSumOfNextValues() => ValueHistories
+    .Select(valueHistory => valueHistory.CalculateNextValue())
+    .Sum();
+
   public static OasisReport Parse(string[] oasisReportInput)
   {
     var valueHistories = new List<ValueHistory>();
@@ -51,7 +80,7 @@ public class ValueHistory(
 
     while (
       allHistoricalValues.Count is 0 ||
-      allHistoricalValues.Last().Sum() is not 0
+      allHistoricalValues.Last().Any(value => value is not 0)
     )
     {
       var historicalValues = CalculateDifferences(currentValues);
@@ -65,7 +94,23 @@ public class ValueHistory(
   public long CalculateNextValue()
   {
     var historicalValues = CalculateHistory();
-    var values = historicalValues.Prepend(Values).ToList();
-    return 0;
+    var values = historicalValues.Prepend(Values).Reverse().ToList();
+
+    for (var i = 0; i < values.Count; i++)
+    {
+      var currentValues = values[i];
+
+      if (i is 0)
+      {
+        currentValues.Add(0);
+        continue;
+      }
+
+      var previousValues = values[i - 1];
+
+      currentValues.Add(currentValues.Last() + previousValues.Last());
+    }
+
+    return values.Last().Last();
   }
 }