initial commit, day 10

dotnet/09/09.cs

@@ -0,0 +1,138 @@
+using System.Numerics;
+using System.Security.Cryptography.X509Certificates;
+
+// Main1();
+Main2();
+
+void Main1()
+{
+    var data = LoadData1(Path.Join("..", "..", "09a.txt"));
+    int i = 0;
+    int j = data.Length - 1;
+    while (i < j)
+    {
+        if (data[i] == -1)
+        {
+            while (data[j] == -1)
+                j--;
+            data[i] = data[j];
+            data[j] = -1;
+        }
+        i++;
+    }
+    i--;
+    BigInteger checksum = 0;
+    while (i >= 0)
+    {
+        if (data[i] < 0)
+            throw new Exception($"Index {i} Value {data[i]}");
+        checksum += i * data[i];
+        i--;
+    }
+    Console.WriteLine($"Part1: {checksum,15}");
+}
+
+void Main2()
+{
+    var (files, empties) = LoadData2(Path.Join("..", "..", "09a.txt"));
+    for (int i = files.Count-1; i >= 1; i--)
+    {
+        var file = files[i];
+        for (int j = 0; j < empties.Count; j++)
+        {
+            var empty = empties[j];
+            if (file.Location < empty.Location)
+                break;
+            if (file.Length <= empty.Length)
+            {
+                file.Location = empty.Location;
+                empties[j] = new(empty.Location + file.Length, empty.Length - file.Length);
+                break;
+            }
+        }
+    }
+    //long is big enough but changing it didn't help execution time so...
+    BigInteger checksum = 0;
+    foreach (var f in files)
+    {
+        for (int i = 0; i < f.Length; i++)
+        {
+            checksum += f.Id * (f.Location + i);
+        }
+    }
+    Console.WriteLine($"Part2: {checksum,15}");
+}
+
+int[] LoadData1(string filepath)
+{
+    int next_id = 0;
+    bool next_is_blank = false;
+    int GetId()
+    {
+        if (next_is_blank)
+        {
+            next_is_blank = false;
+            return -1;
+        }
+        else
+        {
+            next_is_blank = true;
+            return next_id++;
+        }
+    }
+    var data = File.ReadAllText(filepath).Trim().SelectMany(c => Enumerable.Repeat(GetId(), c - '0')).ToArray();
+    return data;
+}
+
+(List<Filelike>,List<Empty>) LoadData2(string filepath)
+{
+    short next_id = 0;
+    bool next_is_blank = false;
+    int location = 0;
+    List<Filelike> files = [];
+    List<Empty> empties = [];
+    foreach (char c in File.ReadAllText(filepath).Trim())
+    {
+        int length = c - '0';
+        if (next_is_blank)
+        {
+            if (length > 0)
+                empties.Add(new (location, length));
+            next_is_blank = false;
+            location += length;
+        }
+        else
+        {
+            next_is_blank = true;
+            if (length > 0)
+                files.Add(new (location, length, next_id));
+            location += length;
+            next_id++;
+        }
+    }
+    return (files,empties);
+}
+
+class Filelike(int Location, int Length, short Id)
+{
+    public int Location = Location;
+    public int Length = Length;
+    public short Id = Id;
+}
+class Empty(int Location, int Length)
+{
+    public int Location = Location;
+    public int Length = Length;
+}
+
+// class Filelike(int Location, int Length, int Id)
+// {
+//     public int Location = Location;
+//     public int Length = Length;
+//     public int Id = Id;
+// }
+// class Empty(int Location, int Length)
+// {
+//     public int Location = Location;
+//     public int Length = Length;
+// }