Day 11

Day10.cs

@@ -1,4 +1,4 @@
-#define Day10
+// #define Day10
 #if Day10
 var bracketScores = new Dictionary<char, int>() { { ')', 3 }, { ']', 57 }, { '}', 1197 }, { '>', 25137 } };
 var closingBracketExpect = new Dictionary<char, char>() { { ')', '(' }, { ']', '[' }, { '}', '{' }, { '>', '<' } };

Day11.cs

@@ -0,0 +1,47 @@
+#define Day11
+#if Day11
+using AoC2021;
+
+const int GRID_SIZE = 10;
+
+var grid = File.ReadAllLines("day11/input")
+    .SelectMany((l,row) =>
+        l.Select((c, col) => new {pos = new Pos(row, col), v = int.Parse(c.ToString())}))
+    .ToDictionary(x => x.pos, x => x.v);
+
+long flashes = 0;
+int flashesPerStep = 0;
+
+int count = 0;
+while (true) {
+    flashesPerStep = 0;
+    grid = grid.ToDictionary(x => x.Key, x => x.Value + 1);
+    grid.Keys.ForEachAsList(p => grid = flash(p, grid));
+    count++;
+    if (flashesPerStep == 100) { Console.WriteLine(count); break; }
+
+    if (count == 100) { Console.WriteLine(flashes); }
+}
+
+Dictionary<Pos, int> flash(Pos cur, Dictionary<Pos, int> grid) {
+    if (grid[cur] < 10) {
+        return grid;
+    }
+
+    flashes++;
+    flashesPerStep++;
+    grid[cur] = 0;
+
+    var adjacent = GetAdjacent(cur);
+    adjacent.Where(a => grid[a] != 0).ForEachAsList(a => grid[a] += 1);
+    adjacent.Where(a=> grid[a] > 9).ForEachAsList(a => grid = flash(a, grid));
+    return grid;
+}
+
+List<Pos> GetAdjacent(Pos p) => new List<Pos>() {
+        new(p.row-1, p.col), new(p.row-1, p.col+1), new(p.row-1, p.col-1),
+        new(p.row+1, p.col), new(p.row+1, p.col+1), new(p.row+1, p.col-1),
+        new(p.row, p.col+1), new(p.row, p.col-1),
+    }.Where(x => x.row >= 0 && x.row < GRID_SIZE && x.col >= 0 && x.col < GRID_SIZE).ToList();
+record Pos(int row, int col);
+#endif

day11/input

@@ -0,0 +1,10 @@
+2344671212
+6611742681
+5575575573
+3167848536
+1353827311
+4416463266
+2624761615
+1786561263
+3622643215
+4143284653