From 37b740f07a5545292a81887d6450f113c4219ecc Mon Sep 17 00:00:00 2001
From: ktkk <dezuttereluka@gmail.com>
Date: Thu, 11 Dec 2025 12:15:11 +0000
Subject: [PATCH 1/4] Finish day11, part 1

---
 src/days/day11.zig       |  76 ++++-
 src/days/input/day11.txt | 609 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 683 insertions(+), 2 deletions(-)
 create mode 100755 src/days/input/day11.txt

diff --git a/src/days/day11.zig b/src/days/day11.zig
index d16d9d5..cfbf883 100644
--- a/src/days/day11.zig
+++ b/src/days/day11.zig
@@ -1,7 +1,79 @@
 const std = @import("std");
 
-pub const title = "Day 11";
+pub const title = "Day 11: Reactor";
 
-pub fn run(_: std.mem.Allocator) !void {
+pub fn run(allocator: std.mem.Allocator) !void {
+    const input = @embedFile("./input/day11.txt");
+    //const input =
+    //    \\aaa: you hhh
+    //    \\you: bbb ccc
+    //    \\bbb: ddd eee
+    //    \\ccc: ddd eee fff
+    //    \\ddd: ggg
+    //    \\eee: out
+    //    \\fff: out
+    //    \\ggg: out
+    //    \\hhh: ccc fff iii
+    //    \\iii: out
+    //    ;
+
+    var lines = std.mem.tokenizeScalar(u8, input, '\n');
+
+    var devices: std.StringHashMap([][]const u8) = .init(allocator);
+    defer {
+        var outputs_iter = devices.valueIterator();
+        while (outputs_iter.next()) |value| {
+            allocator.free(value.*);
+        }
+        devices.deinit();
+    }
+
+    while (lines.next()) |line| {
+        const device = line[0..3];
+        std.debug.print("device = {s}\n", .{device});
+
+        var outputs: std.ArrayList([]const u8) = .empty;
+        defer outputs.deinit(allocator);
+
+        var outputs_iter = std.mem.tokenizeScalar(u8, line[5..], ' ');
+        while (outputs_iter.next()) |output| {
+            try outputs.append(allocator, output);
+        }
+
+        const outputs_slice = try outputs.toOwnedSlice(allocator);
+        errdefer allocator.free(outputs_slice);
+
+        try devices.put(device, outputs_slice);
+    }
+
+    var paths_to_out: usize = 0;
+    visitOutputs("you", devices, &paths_to_out);
+
+    var buffer: [8]u8 = undefined;
+    var stdout_writer = std.fs.File.stdout().writer(&buffer);
+    const stdout = &stdout_writer.interface;
+
+    try stdout.print("{d}\n", .{paths_to_out});
+
+    try stdout.flush();
+}
+
+fn visitOutputs(
+    start: []const u8,
+    devices: std.StringHashMap([][]const u8),
+    paths_to_out: *usize,
+) void {
+    const device = devices.get(start);
+    if (device) |outputs| {
+        for (outputs) |output| {
+            if (std.mem.eql(u8, output, "out")) {
+                paths_to_out.* += 1;
+            } else {
+                visitOutputs(output, devices, paths_to_out);
+            }
+        }
+    } else {
+        std.debug.print("device {s} not found\n", .{start});
+    }
 }
 
diff --git a/src/days/input/day11.txt b/src/days/input/day11.txt
new file mode 100755
index 0000000..1c6713e
--- /dev/null
+++ b/src/days/input/day11.txt
@@ -0,0 +1,609 @@
+smx: otc
+mmh: gvp
+gbo: hyf alz
+laa: vky qjq
+vrn: tbs tsr jix
+xyl: xel eur wdj
+sxm: out
+wsd: kua hpv jep
+qsj: ulu xel eur wdj
+xwa: mtd xxf hnw
+kai: ehr kaj
+uuj: you
+owb: ixr bps pim eez ejn syt qrx hxw vsy ghl gfu cgh mpk kfj
+vky: owb wlw qic
+ysd: mkp jbf btz xgg gbk tvg iju amm dws ykz azc blh xld rpr uek rcl zzy jhu
+rbc: ski xyl sdx wpw
+zmc: pal lwb rns hex
+cuu: vyo
+bqf: kmy exx ish
+jbv: ysa
+aog: ayv kwq
+fcq: qic xss owb
+hyg: out
+xoz: llx kra cqn bzn swe tdo vnz zos duw
+gnq: eya
+qmk: fcq lyd
+ggp: brz eya
+oit: yyy quh brz
+hjl: dtj lnc jps fyr
+sqg: xbz upq
+nil: diq
+xqa: jei ipw tkt
+ond: fft jko dqj pxe
+and: ahn izm esa
+cqf: xss
+rqa: ryb rwu ono fyb
+jps: byj fmv shn
+ccg: ond afk tbu
+dta: ctq jbw whr smq
+ztx: hlm ctr vgo maf fkj
+sdx: xel eur
+xwb: dds
+clh: ktb
+rtn: quh eya
+dac: nxc vug eou
+nvh: kmf yga wtv
+xgw: kep unr lju mtm
+mdx: qmk fwk fbd
+tbu: fft dqj pxe
+vil: lyz aek
+ona: zjk ovx dmv laa
+bld: zbs
+rms: vjs znm
+oku: brz yyy
+bzn: dmc fwa ykh vrn axj
+uzl: ayv fuz qhs kwq
+bhz: ggv
+kfj: xqa ucr akl
+koi: szi
+mvo: dqp kjr rbc
+rof: vgo hlm
+ixt: jws nxc vug
+ycf: out
+dmc: tsr
+nam: mvo
+rkj: quh yyy eya brz
+qxk: uty
+lwb: phc esx
+fqf: isr dax
+eou: lqz ysd
+lbb: out
+hyf: fgh wem yen taw
+dfv: nzl
+pnh: lai
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+guf: shn
+lmw: hlu mhq
+jff: ngn gye
+xxj: guf dtj lnc
+fbd: fcq lyd
+idw: cmg phc
+zbs: hjl
+lqz: blh ttg ykz jhu zzy uek rcl bld xgg gbk mkp amm iju tvg
+shn: goi
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+odf: yey ggp jtc
+rkk: zyi ubs
+fyr: fmv vtv
+pxe: ztx mmi
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+mvj: gtx rni
+ryw: iby llv
+npf: quh brz lvi
+zad: ssa tsh
+esx: lqz ysd
+mwp: mmh
+alz: wem yen
+kra: luk nil
+xmj: smx
+dej: kew

From f85eda4e870dba5bd8fe6b5b1f2ff05c9167856d Mon Sep 17 00:00:00 2001
From: ktkk <dezuttereluka@gmail.com>
Date: Thu, 11 Dec 2025 15:48:33 +0000
Subject: [PATCH 2/4] WIP: implement part 2

---
 src/days/day11.zig | 39 +++++++++++++++++++++++++++------------
 1 file changed, 27 insertions(+), 12 deletions(-)

diff --git a/src/days/day11.zig b/src/days/day11.zig
index cfbf883..2525215 100644
--- a/src/days/day11.zig
+++ b/src/days/day11.zig
@@ -5,16 +5,19 @@ pub const title = "Day 11: Reactor";
 pub fn run(allocator: std.mem.Allocator) !void {
     const input = @embedFile("./input/day11.txt");
     //const input =
-    //    \\aaa: you hhh
-    //    \\you: bbb ccc
-    //    \\bbb: ddd eee
-    //    \\ccc: ddd eee fff
-    //    \\ddd: ggg
-    //    \\eee: out
-    //    \\fff: out
+    //    \\svr: aaa bbb
+    //    \\aaa: fft
+    //    \\fft: ccc
+    //    \\bbb: tty
+    //    \\tty: ccc
+    //    \\ccc: ddd eee
+    //    \\ddd: hub
+    //    \\hub: fff
+    //    \\eee: dac
+    //    \\dac: fff
+    //    \\fff: ggg hhh
     //    \\ggg: out
-    //    \\hhh: ccc fff iii
-    //    \\iii: out
+    //    \\hhh: out
     //    ;
 
     var lines = std.mem.tokenizeScalar(u8, input, '\n');
@@ -47,7 +50,7 @@ pub fn run(allocator: std.mem.Allocator) !void {
     }
 
     var paths_to_out: usize = 0;
-    visitOutputs("you", devices, &paths_to_out);
+    visitOutputs("svr", devices, &paths_to_out, false, false);
 
     var buffer: [8]u8 = undefined;
     var stdout_writer = std.fs.File.stdout().writer(&buffer);
@@ -62,14 +65,26 @@ fn visitOutputs(
     start: []const u8,
     devices: std.StringHashMap([][]const u8),
     paths_to_out: *usize,
+    visited_fft: bool,
+    visited_dac: bool,
 ) void {
     const device = devices.get(start);
     if (device) |outputs| {
         for (outputs) |output| {
             if (std.mem.eql(u8, output, "out")) {
-                paths_to_out.* += 1;
+                std.debug.print("found out! (fft = {any}, dac = {any})\n", .{visited_fft, visited_dac});
+                if (visited_fft and visited_dac) {
+                    std.debug.print("visited fft and dac\n", .{});
+                    paths_to_out.* += 1;
+                }
+            } else if (std.mem.eql(u8, output, "fft")) {
+                std.debug.print("found fft!\n", .{});
+                visitOutputs(output, devices, paths_to_out, true, visited_dac);
+            } else if (std.mem.eql(u8, output, "dac")) {
+                std.debug.print("found dac!\n", .{});
+                visitOutputs(output, devices, paths_to_out, visited_fft, true);
             } else {
-                visitOutputs(output, devices, paths_to_out);
+                visitOutputs(output, devices, paths_to_out, visited_fft, visited_dac);
             }
         }
     } else {

From 76b70d3c6b3251b5a6352c7242a955818bf152fe Mon Sep 17 00:00:00 2001
From: ktkk <dezuttereluka@gmail.com>
Date: Thu, 11 Dec 2025 16:30:51 +0000
Subject: [PATCH 3/4] WIP: implement part 2

---
 src/days/day11.zig | 49 +++++++++++++++++++++++++++++-----------------
 1 file changed, 31 insertions(+), 18 deletions(-)

diff --git a/src/days/day11.zig b/src/days/day11.zig
index 2525215..b8084d4 100644
--- a/src/days/day11.zig
+++ b/src/days/day11.zig
@@ -5,6 +5,18 @@ pub const title = "Day 11: Reactor";
 pub fn run(allocator: std.mem.Allocator) !void {
     const input = @embedFile("./input/day11.txt");
     //const input =
+    //    \\aaa: you hhh
+    //    \\you: bbb ccc
+    //    \\bbb: ddd eee
+    //    \\ccc: ddd eee fff
+    //    \\ddd: ggg
+    //    \\eee: out
+    //    \\fff: out
+    //    \\ggg: out
+    //    \\hhh: ccc fff iii
+    //    \\iii: out
+    //    ;
+    //const input =
     //    \\svr: aaa bbb
     //    \\aaa: fft
     //    \\fft: ccc
@@ -49,8 +61,11 @@ pub fn run(allocator: std.mem.Allocator) !void {
         try devices.put(device, outputs_slice);
     }
 
+    var cache: std.StringHashMap(usize) = .init(allocator);
+    defer cache.deinit();
+
     var paths_to_out: usize = 0;
-    visitOutputs("svr", devices, &paths_to_out, false, false);
+    try visitOutputs("svr", "fft", devices, &cache, &paths_to_out);
 
     var buffer: [8]u8 = undefined;
     var stdout_writer = std.fs.File.stdout().writer(&buffer);
@@ -63,30 +78,28 @@ pub fn run(allocator: std.mem.Allocator) !void {
 
 fn visitOutputs(
     start: []const u8,
+    end: []const u8,
     devices: std.StringHashMap([][]const u8),
-    paths_to_out: *usize,
-    visited_fft: bool,
-    visited_dac: bool,
-) void {
+    cache: *std.StringHashMap(usize),
+    paths_to_end: *usize,
+) !void {
+    if (cache.get(start)) |result| {
+        paths_to_end.* += result;
+        return;
+    }
+
+    var paths: usize = 0;
     const device = devices.get(start);
     if (device) |outputs| {
         for (outputs) |output| {
-            if (std.mem.eql(u8, output, "out")) {
-                std.debug.print("found out! (fft = {any}, dac = {any})\n", .{visited_fft, visited_dac});
-                if (visited_fft and visited_dac) {
-                    std.debug.print("visited fft and dac\n", .{});
-                    paths_to_out.* += 1;
-                }
-            } else if (std.mem.eql(u8, output, "fft")) {
-                std.debug.print("found fft!\n", .{});
-                visitOutputs(output, devices, paths_to_out, true, visited_dac);
-            } else if (std.mem.eql(u8, output, "dac")) {
-                std.debug.print("found dac!\n", .{});
-                visitOutputs(output, devices, paths_to_out, visited_fft, true);
+            if (std.mem.eql(u8, output, end)) {
+                paths += 1;
             } else {
-                visitOutputs(output, devices, paths_to_out, visited_fft, visited_dac);
+                try visitOutputs(output, end, devices, cache, &paths);
             }
         }
+        try cache.put(start, paths);
+        paths_to_end.* += paths;
     } else {
         std.debug.print("device {s} not found\n", .{start});
     }

From 524b451399f6cd8bcf77db8034b70982c6d77108 Mon Sep 17 00:00:00 2001
From: ktkk <dezuttereluka@gmail.com>
Date: Thu, 11 Dec 2025 18:40:52 +0000
Subject: [PATCH 4/4] Finish day11, part 2

---
 src/days/day11.zig | 31 ++++++++++++++++++++++---------
 1 file changed, 22 insertions(+), 9 deletions(-)

diff --git a/src/days/day11.zig b/src/days/day11.zig
index b8084d4..5e7686a 100644
--- a/src/days/day11.zig
+++ b/src/days/day11.zig
@@ -63,15 +63,29 @@ pub fn run(allocator: std.mem.Allocator) !void {
 
     var cache: std.StringHashMap(usize) = .init(allocator);
     defer cache.deinit();
+    try cache.ensureTotalCapacity(devices.count());
 
-    var paths_to_out: usize = 0;
-    try visitOutputs("svr", "fft", devices, &cache, &paths_to_out);
+    const dac_to_fft = try visitOutputs("dac", "fft", devices, &cache);
+    const svr_to_fft = try visitOutputs("svr", "fft", devices, &cache);
+    cache.clearRetainingCapacity();
+
+    const to_fft = if (dac_to_fft == 0) svr_to_fft else dac_to_fft;
+
+    const dac_start = if (dac_to_fft == 0) "fft" else "svr";
+    const end_start = if (dac_to_fft == 0) "dac" else "fft";
+
+    const to_dac = try visitOutputs(dac_start, "dac", devices, &cache);
+    cache.clearRetainingCapacity();
+
+    const to_end = try visitOutputs(end_start, "out", devices, &cache);
+
+    const result = to_fft * to_dac * to_end;
 
     var buffer: [8]u8 = undefined;
     var stdout_writer = std.fs.File.stdout().writer(&buffer);
     const stdout = &stdout_writer.interface;
 
-    try stdout.print("{d}\n", .{paths_to_out});
+    try stdout.print("{d}\n", .{result});
 
     try stdout.flush();
 }
@@ -81,11 +95,9 @@ fn visitOutputs(
     end: []const u8,
     devices: std.StringHashMap([][]const u8),
     cache: *std.StringHashMap(usize),
-    paths_to_end: *usize,
-) !void {
+) !usize {
     if (cache.get(start)) |result| {
-        paths_to_end.* += result;
-        return;
+        return result;
     }
 
     var paths: usize = 0;
@@ -95,13 +107,14 @@ fn visitOutputs(
             if (std.mem.eql(u8, output, end)) {
                 paths += 1;
             } else {
-                try visitOutputs(output, end, devices, cache, &paths);
+                paths += try visitOutputs(output, end, devices, cache);
             }
         }
         try cache.put(start, paths);
-        paths_to_end.* += paths;
+        return paths;
     } else {
         std.debug.print("device {s} not found\n", .{start});
+        return 0;
     }
 }