diff --git a/day1.zig b/day1.zig
index 8888312..5c79583 100644
--- a/day1.zig
+++ b/day1.zig
@@ -2,7 +2,9 @@ const std = @import("std");
 
 const utils = @import("lib/utils.zig");
 
-const filename = "inputs/day1.txt";
+const day = "1";
+
+const filename = "inputs/day" ++ day ++ ".txt";
 
 pub fn main() !void {
     var gpa = std.heap.GeneralPurposeAllocator(.{}){};
@@ -14,7 +16,7 @@ pub fn main() !void {
 
         const result = try part1(alloc, file_reader.reader());
 
-        try std.io.getStdOut().writer().print("Day 1, part 1: {}\n", .{result});
+        try std.io.getStdOut().writer().print("Day " ++ day ++ ", part 1: {}\n", .{result});
     }
 
     {
@@ -23,7 +25,7 @@ pub fn main() !void {
 
         const result = try part2(alloc, file_reader.reader());
 
-        try std.io.getStdOut().writer().print("Day 1, part 1: {}\n", .{result});
+        try std.io.getStdOut().writer().print("Day " ++ day ++ ", part 2: {}\n", .{result});
     }
 }
 
diff --git a/day10.zig b/day10.zig
index 656012a..566d186 100644
--- a/day10.zig
+++ b/day10.zig
@@ -4,7 +4,9 @@ const utils = @import("lib/utils.zig");
 
 const spice = @import("lib/spice.zig");
 
-const filename = "inputs/day10.txt";
+const day = "10";
+
+const filename = "inputs/day" ++ day ++ ".txt";
 
 pub fn main() !void {
     var gpa = std.heap.GeneralPurposeAllocator(.{}){};
@@ -16,7 +18,7 @@ pub fn main() !void {
 
         const result = try part1(alloc, file_reader.reader());
 
-        try std.io.getStdOut().writer().print("Day 10, part 1: {}\n", .{result});
+        try std.io.getStdOut().writer().print("Day " ++ day ++ ", part 1: {}\n", .{result});
     }
 
     {
@@ -25,7 +27,7 @@ pub fn main() !void {
 
         const result = try part2(alloc, file_reader.reader());
 
-        try std.io.getStdOut().writer().print("Day 10, part 2: {}\n", .{result});
+        try std.io.getStdOut().writer().print("Day " ++ day ++ ", part 2: {}\n", .{result});
     }
 }
 
diff --git a/day11.zig b/day11.zig
new file mode 100644
index 0000000..7c28dae
--- /dev/null
+++ b/day11.zig
@@ -0,0 +1,154 @@
+const std = @import("std");
+
+const utils = @import("lib/utils.zig");
+
+const spice = @import("lib/spice.zig");
+
+const day = "11";
+
+const filename = "inputs/day" ++ day ++ ".txt";
+
+pub fn main() !void {
+    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+    const alloc = gpa.allocator();
+
+    {
+        const file_reader = try utils.FileReader.init(alloc, filename);
+        defer file_reader.deinit();
+
+        const result = try part1(alloc, file_reader.reader());
+
+        try std.io.getStdOut().writer().print("Day " ++ day ++ ", part 1: {}\n", .{result});
+    }
+
+    {
+        const file_reader = try utils.FileReader.init(alloc, filename);
+        defer file_reader.deinit();
+
+        const result = try part2(alloc, file_reader.reader());
+
+        try std.io.getStdOut().writer().print("Day " ++ day ++ ", part 2: {}\n", .{result});
+    }
+}
+
+const CacheKey = struct { n: u64, depth: u8 };
+
+fn countStones(n: u64, remaining_depth: u8, cache: *std.AutoHashMap(CacheKey, u64)) u64 {
+    if (remaining_depth == 0) {
+        return 1;
+    }
+
+    if (cache.get(.{ .n = n, .depth = remaining_depth })) |result| {
+        return result;
+    }
+
+    if (n == 0) {
+        const result = countStones(1, remaining_depth - 1, cache);
+        cache.put(.{ .n = n, .depth = remaining_depth }, result) catch @panic("cache put failed");
+
+        return result;
+        // try countStones(count, 1, remaining_depth);
+        // return;
+    }
+
+    if (utils.num_digits(n) % 2 == 0) {
+        const num_digits = utils.num_digits(n);
+
+        const pow10 = std.math.powi(u32, 10, num_digits / 2) catch @panic("powi failed");
+
+        const left = n / pow10;
+        const right = n % pow10;
+
+        // return countStones(left, remaining_depth - 1, cache) + countStones(right, remaining_depth - 1, cache);
+
+        const left_result = countStones(left, remaining_depth - 1, cache);
+        const right_result = countStones(right, remaining_depth - 1, cache);
+
+        const result = left_result + right_result;
+
+        cache.put(.{ .n = n, .depth = remaining_depth }, result) catch @panic("cache put failed");
+
+        return left_result + right_result;
+
+        // try countStones(count, left, remaining_depth - 1);
+        // try countStones(count, right, remaining_depth - 1);
+        // return;
+    }
+
+    const result = countStones(n * 2024, remaining_depth - 1, cache);
+    cache.put(.{ .n = n, .depth = remaining_depth }, result) catch @panic("cache put failed");
+
+    return result;
+
+    // try countStones(count, 2024 * n, remaining_depth - 1);
+}
+
+fn part1(alloc: std.mem.Allocator, reader: anytype) !u64 {
+    const input = try reader.readAllAlloc(alloc, std.math.maxInt(usize));
+    defer alloc.free(input);
+
+    var count: u64 = 0;
+
+    var cache = std.AutoHashMap(CacheKey, u64).init(alloc);
+    defer cache.deinit();
+
+    var number_parser = utils.numberParser(u64, input);
+
+    while (try number_parser.next()) |n| {
+        count += countStones(n, 25, &cache);
+    }
+
+    return count;
+}
+
+fn part2(alloc: std.mem.Allocator, reader: anytype) !u64 {
+    const input = try reader.readAllAlloc(alloc, std.math.maxInt(usize));
+    defer alloc.free(input);
+
+    var count: u64 = 0;
+
+    var cache = std.AutoHashMap(CacheKey, u64).init(alloc);
+    defer cache.deinit();
+
+    var number_parser = utils.numberParser(u64, input);
+
+    while (try number_parser.next()) |n| {
+        count += countStones(n, 75, &cache);
+    }
+
+    return count;
+}
+
+test "part1 example" {
+    const alloc = std.testing.allocator;
+
+    const example = "125 17";
+
+    var stream = std.io.fixedBufferStream(example);
+
+    const result = try part1(alloc, stream.reader());
+
+    try std.testing.expectEqual(55312, result);
+}
+
+test "part1 input" {
+    const alloc = std.testing.allocator;
+
+    const file_reader = try utils.FileReader.init(alloc, filename);
+    defer file_reader.deinit();
+
+    const result = try part1(alloc, file_reader.reader());
+
+    try std.testing.expectEqual(193899, result);
+}
+
+test "part2 input" {
+    const alloc = std.testing.allocator;
+
+    const file_reader = try utils.FileReader.init(alloc, filename);
+    defer file_reader.deinit();
+
+    const result = try part2(alloc, file_reader.reader());
+
+    try std.testing.expectEqual(229682160383225, result);
+}
diff --git a/day2.zig b/day2.zig
index bef5bfc..36bfcef 100644
--- a/day2.zig
+++ b/day2.zig
@@ -2,7 +2,9 @@ const std = @import("std");
 
 const utils = @import("lib/utils.zig");
 
-const filename = "inputs/day2.txt";
+const day = "2";
+
+const filename = "inputs/day" ++ day ++ ".txt";
 
 pub fn main() !void {
     var gpa = std.heap.GeneralPurposeAllocator(.{}){};
@@ -14,7 +16,7 @@ pub fn main() !void {
 
         const result = try part1(alloc, file_reader.reader());
 
-        try std.io.getStdOut().writer().print("Day 2, part 1: {}\n", .{result});
+        try std.io.getStdOut().writer().print("Day " ++ day ++ ", part 1: {}\n", .{result});
     }
 
     {
@@ -23,7 +25,7 @@ pub fn main() !void {
 
         const result = try part2(alloc, file_reader.reader());
 
-        try std.io.getStdOut().writer().print("Day 2, part 2: {}\n", .{result});
+        try std.io.getStdOut().writer().print("Day " ++ day ++ ", part 2: {}\n", .{result});
     }
 }
 
diff --git a/day3.zig b/day3.zig
index 32d1ed7..37307e0 100644
--- a/day3.zig
+++ b/day3.zig
@@ -4,7 +4,9 @@ const utils = @import("lib/utils.zig");
 
 const isDigit = std.ascii.isDigit;
 
-const filename = "inputs/day3.txt";
+const day = "3";
+
+const filename = "inputs/day" ++ day ++ ".txt";
 
 pub fn main() !void {
     var gpa = std.heap.GeneralPurposeAllocator(.{}){};
@@ -16,7 +18,7 @@ pub fn main() !void {
 
         const result = try part1(alloc, file_reader.reader());
 
-        try std.io.getStdOut().writer().print("Day 3, part 1: {}\n", .{result});
+        try std.io.getStdOut().writer().print("Day " ++ day ++ ", part 1: {}\n", .{result});
     }
 
     {
@@ -25,7 +27,7 @@ pub fn main() !void {
 
         const result = try part2(alloc, file_reader.reader());
 
-        try std.io.getStdOut().writer().print("Day 3, part 2: {}\n", .{result});
+        try std.io.getStdOut().writer().print("Day " ++ day ++ ", part 2: {}\n", .{result});
     }
 }
 
diff --git a/day4.zig b/day4.zig
index 504b0a3..ab6dd23 100644
--- a/day4.zig
+++ b/day4.zig
@@ -2,7 +2,9 @@ const std = @import("std");
 
 const utils = @import("lib/utils.zig");
 
-const filename = "inputs/day4.txt";
+const day = "4";
+
+const filename = "inputs/day" ++ day ++ ".txt";
 
 pub fn main() !void {
     var gpa = std.heap.GeneralPurposeAllocator(.{}){};
@@ -14,7 +16,7 @@ pub fn main() !void {
 
         const result = try part1(alloc, file_reader.reader());
 
-        try std.io.getStdOut().writer().print("Day 4, part 1: {}\n", .{result});
+        try std.io.getStdOut().writer().print("Day " ++ day ++ ", part 1: {}\n", .{result});
     }
 
     {
@@ -23,7 +25,7 @@ pub fn main() !void {
 
         const result = try part2(alloc, file_reader.reader());
 
-        try std.io.getStdOut().writer().print("Day 4, part 2: {}\n", .{result});
+        try std.io.getStdOut().writer().print("Day " ++ day ++ ", part 2: {}\n", .{result});
     }
 }
 
diff --git a/day5.zig b/day5.zig
index dbb14c7..4706bb6 100644
--- a/day5.zig
+++ b/day5.zig
@@ -4,7 +4,9 @@ const utils = @import("lib/utils.zig");
 
 const List = std.DoublyLinkedList(u8);
 
-const filename = "inputs/day5.txt";
+const day = "5";
+
+const filename = "inputs/day" ++ day ++ ".txt";
 
 pub fn main() !void {
     var gpa = std.heap.GeneralPurposeAllocator(.{}){};
@@ -16,7 +18,7 @@ pub fn main() !void {
 
         const result = try part1(alloc, file_reader.reader());
 
-        try std.io.getStdOut().writer().print("Day 5, part 1: {}\n", .{result});
+        try std.io.getStdOut().writer().print("Day " ++ day ++ ", part 1: {}\n", .{result});
     }
 
     {
@@ -25,7 +27,7 @@ pub fn main() !void {
 
         const result = try part2(alloc, file_reader.reader());
 
-        try std.io.getStdOut().writer().print("Day 5, part 2: {}\n", .{result});
+        try std.io.getStdOut().writer().print("Day " ++ day ++ ", part 2: {}\n", .{result});
     }
 }
 
diff --git a/day6.zig b/day6.zig
index 3bc18f1..0793ac2 100644
--- a/day6.zig
+++ b/day6.zig
@@ -2,7 +2,9 @@ const std = @import("std");
 
 const utils = @import("lib/utils.zig");
 
-const filename = "inputs/day6.txt";
+const day = "6";
+
+const filename = "inputs/day" ++ day ++ ".txt";
 
 pub fn main() !void {
     var gpa = std.heap.GeneralPurposeAllocator(.{}){};
@@ -14,7 +16,7 @@ pub fn main() !void {
 
         const result = try part1(alloc, file_reader.reader());
 
-        try std.io.getStdOut().writer().print("Day 6, part 1: {}\n", .{result});
+        try std.io.getStdOut().writer().print("Day " ++ day ++ ", part 1: {}\n", .{result});
     }
 
     {
@@ -23,7 +25,7 @@ pub fn main() !void {
 
         const result = try part2(alloc, file_reader.reader());
 
-        try std.io.getStdOut().writer().print("Day 6, part 2: {}\n", .{result});
+        try std.io.getStdOut().writer().print("Day " ++ day ++ ", part 2: {}\n", .{result});
     }
 }
 
diff --git a/day7.zig b/day7.zig
index 6d110df..0e81391 100644
--- a/day7.zig
+++ b/day7.zig
@@ -4,7 +4,9 @@ const utils = @import("lib/utils.zig");
 
 const spice = @import("lib/spice.zig");
 
-const filename = "inputs/day7.txt";
+const day = "7";
+
+const filename = "inputs/day" ++ day ++ ".txt";
 
 pub fn main() !void {
     var gpa = std.heap.GeneralPurposeAllocator(.{}){};
@@ -16,7 +18,7 @@ pub fn main() !void {
 
         const result = try part1(alloc, file_reader.reader());
 
-        try std.io.getStdOut().writer().print("Day 7, part 1: {}\n", .{result});
+        try std.io.getStdOut().writer().print("Day " ++ day ++ ", part 1: {}\n", .{result});
     }
 
     {
@@ -25,7 +27,7 @@ pub fn main() !void {
 
         const result = try part2(alloc, file_reader.reader());
 
-        try std.io.getStdOut().writer().print("Day 7, part 2: {}\n", .{result});
+        try std.io.getStdOut().writer().print("Day " ++ day ++ ", part 2: {}\n", .{result});
     }
 }
 
diff --git a/day8.zig b/day8.zig
index 9fe2b66..0885f8b 100644
--- a/day8.zig
+++ b/day8.zig
@@ -4,7 +4,9 @@ const utils = @import("lib/utils.zig");
 
 const spice = @import("lib/spice.zig");
 
-const filename = "inputs/day8.txt";
+const day = "8";
+
+const filename = "inputs/day" ++ day ++ ".txt";
 
 pub fn main() !void {
     var gpa = std.heap.GeneralPurposeAllocator(.{}){};
@@ -16,7 +18,7 @@ pub fn main() !void {
 
         const result = try part1(alloc, file_reader.reader());
 
-        try std.io.getStdOut().writer().print("Day 8, part 1: {}\n", .{result});
+        try std.io.getStdOut().writer().print("Day " ++ day ++ ", part 1: {}\n", .{result});
     }
 
     {
@@ -25,7 +27,7 @@ pub fn main() !void {
 
         const result = try part2(alloc, file_reader.reader());
 
-        try std.io.getStdOut().writer().print("Day 8, part 2: {}\n", .{result});
+        try std.io.getStdOut().writer().print("Day " ++ day ++ ", part 2: {}\n", .{result});
     }
 }
 
diff --git a/day9.zig b/day9.zig
index 506c47b..d8b67d4 100644
--- a/day9.zig
+++ b/day9.zig
@@ -4,7 +4,9 @@ const utils = @import("lib/utils.zig");
 
 const spice = @import("lib/spice.zig");
 
-const filename = "inputs/day9.txt";
+const day = "9";
+
+const filename = "inputs/day" ++ day ++ ".txt";
 
 pub fn main() !void {
     var gpa = std.heap.GeneralPurposeAllocator(.{}){};
@@ -16,7 +18,7 @@ pub fn main() !void {
 
         const result = try part1(alloc, file_reader.reader());
 
-        try std.io.getStdOut().writer().print("Day 9, part 1: {}\n", .{result});
+        try std.io.getStdOut().writer().print("Day " ++ day ++ ", part 1: {}\n", .{result});
     }
 
     {
@@ -25,7 +27,7 @@ pub fn main() !void {
 
         const result = try part2(alloc, file_reader.reader());
 
-        try std.io.getStdOut().writer().print("Day 9, part 2: {}\n", .{result});
+        try std.io.getStdOut().writer().print("Day " ++ day ++ ", part 2: {}\n", .{result});
     }
 }
 
diff --git a/inputs/day11.txt b/inputs/day11.txt
new file mode 100644
index 0000000..d252362
--- /dev/null
+++ b/inputs/day11.txt
@@ -0,0 +1 @@
+0 89741 316108 7641 756 9 7832357 91
diff --git a/lib/utils.zig b/lib/utils.zig
index ed80b7b..e8037dc 100644
--- a/lib/utils.zig
+++ b/lib/utils.zig
@@ -92,12 +92,14 @@ pub fn NumberParser(comptime T: type) type {
     };
 }
 
-pub fn numberParser(comptime T: type, input: []const u8) NumberParser(T) {
-    return NumberParser(T){ .token_it = std.mem.tokenizeScalar(u8, input, ' ') };
+pub fn numberParserWithDelimiter(comptime T: type, input: []const u8, delimiter: u8) NumberParser(T) {
+    const input_trimmed = std.mem.trim(u8, input, "\n");
+
+    return NumberParser(T){ .token_it = std.mem.tokenizeScalar(u8, input_trimmed, delimiter) };
 }
 
-pub fn numberParserWithDelimiter(comptime T: type, input: []const u8, delimiter: u8) NumberParser(T) {
-    return NumberParser(T){ .token_it = std.mem.tokenizeScalar(u8, input, delimiter) };
+pub fn numberParser(comptime T: type, input: []const u8) NumberParser(T) {
+    return numberParserWithDelimiter(T, input, ' ');
 }
 
 pub fn allocGrid(comptime T: type, alloc: std.mem.Allocator, n: usize, m: usize) ![][]T {