From d68ac82e5d1bf693783cbd00cbc97abef13d15ba Mon Sep 17 00:00:00 2001
From: ktkk <dezuttereluka@gmail.com>
Date: Wed, 10 Dec 2025 20:42:15 +0000
Subject: [PATCH] Finish day10, part 1

---
 src/days/day10.zig | 78 +++++++++++++++++++++++++++++++---------------
 1 file changed, 53 insertions(+), 25 deletions(-)

diff --git a/src/days/day10.zig b/src/days/day10.zig
index 8f2b7d4..e70ce94 100644
--- a/src/days/day10.zig
+++ b/src/days/day10.zig
@@ -3,14 +3,27 @@ const std = @import("std");
 pub const title = "Day 10: Factory";
 
 pub fn run(allocator: std.mem.Allocator) !void {
-    //const input = @embedFile("./input/day10.txt");
-    const input =
-        \\[.##.] (3) (1,3) (2) (2,3) (0,2) (0,1) {3,5,4,7}
-        \\[...#.] (0,2,3,4) (2,3) (0,4) (0,1,2) (1,2,3,4) {7,5,12,7,2}
-        \\[.###.#] (0,1,2,3,4) (0,3,4) (0,1,2,4,5) (1,2) {10,11,11,5,10,5}
-        ;
+    const input = @embedFile("./input/day10.txt");
+    //const input =
+    //    \\[.##.] (3) (1,3) (2) (2,3) (0,2) (0,1) {3,5,4,7}
+    //    \\[...#.] (0,2,3,4) (2,3) (0,4) (0,1,2) (1,2,3,4) {7,5,12,7,2}
+    //    \\[.###.#] (0,1,2,3,4) (0,3,4) (0,1,2,4,5) (1,2) {10,11,11,5,10,5}
+    //    ;
+    //const input =
+    //    \\[#...#] (1,3) (2,3,4) (0,2,3) (0,1,2) (2,3) {37,24,60,50,16}
+    //    \\[##...#..] (0,1,3,5,6) (0,1,5) (4) (5,6) (0,4,7) (1,2,5) (3) {23,18,2,26,14,36,25,7}
+    //    ;
 
     var lines = std.mem.tokenizeScalar(u8, input, '\n');
+
+    var accumulator: usize = 0;
+
+    var light_states: std.ArrayList(std.bit_set.IntegerBitSet(Machine.MaxLightCount)) = .empty;
+    defer light_states.deinit(allocator);
+
+    var next_light_states: std.ArrayList(std.bit_set.IntegerBitSet(Machine.MaxLightCount)) = .empty;
+    defer next_light_states.deinit(allocator);
+
     var i: usize = 0;
     while (lines.next()) |line| {
         defer i += 1;
@@ -20,10 +33,41 @@ pub fn run(allocator: std.mem.Allocator) !void {
 
         std.debug.print("{f}\n", .{machine});
 
-        const initial_lights_state: std.bit_set.IntegerBitSet(Machine.MaxLightCount) = .initEmpty();
-        const button_presses = machine.pressButtonSequences(initial_lights_state);
-        std.debug.print("machine {d} required {d} button presses", .{i, button_presses});
+        light_states.clearRetainingCapacity();
+        try light_states.append(allocator, .initEmpty());
+
+        var buttons_pressed: usize = 0;
+
+        outer: while (true) {
+            next_light_states.clearRetainingCapacity();
+
+            buttons_pressed += 1;
+            for (light_states.items) |state| {
+                for (machine.buttons) |button| {
+                    const next_state = state.xorWith(button);
+                    if (next_state.eql(machine.lights_goal)) {
+                        break :outer;
+                    }
+                    try next_light_states.append(allocator, next_state);
+                }
+            }
+
+            light_states.clearRetainingCapacity();
+            try light_states.appendSlice(allocator, next_light_states.items);
+        }
+
+        std.debug.print("machine {d} requires {d} button presses\n", .{i, buttons_pressed});
+
+        accumulator += buttons_pressed;
     }
+
+    var buffer: [64]u8 = undefined;
+    var stdout_writer = std.fs.File.stdout().writer(&buffer);
+    const stdout = &stdout_writer.interface;
+
+    try stdout.print("{d}\n", .{accumulator});
+
+    try stdout.flush();
 }
 
 const Machine = struct {
@@ -83,21 +127,5 @@ const Machine = struct {
             try w.print("({b})", .{button.mask});
         }
     }
-
-    pub fn pressButtonSequences(
-        self: Self,
-        initial_lights_state: std.bit_set.IntegerBitSet(MaxLightCount),
-        buttons_pressed: *usize,
-    ) usize {
-        var button_presses: usize = 0;
-        for (self.buttons) |button| {
-            const result = initial_lights_state.xorWith(button);
-            if (result.mask == self.lights_goal.mask) {
-                return 1;
-            }
-            button_presses += self.pressButtonSequences(result);
-        }
-        return button_presses;
-    }
 };