From 5f524ace81c24a639e026bf09d56fdcdcf3f5b24 Mon Sep 17 00:00:00 2001
From: "Pascal P." <pascal@phelipot.me>
Date: Tue, 6 Jan 2026 15:56:27 +0100
Subject: [PATCH] zig - Implemented day01

---
 zig/src/days/day01.zig | 79 +++++++++++++++++++++++++++++++++++++++---
 zig/src/main.zig       | 12 +++++--
 zig/src/utils/day.zig  |  2 +-
 3 files changed, 85 insertions(+), 8 deletions(-)

diff --git a/zig/src/days/day01.zig b/zig/src/days/day01.zig
index 1c64655..41cbf0a 100644
--- a/zig/src/days/day01.zig
+++ b/zig/src/days/day01.zig
@@ -1,13 +1,84 @@
 const std = @import("std");
 const debug = std.debug;
+const expectEqual = std.testing.expectEqual;
+
 const day = @import("../utils/day.zig");
 
 pub const Day = struct {
     pub const nb = 1;
-    pub fn part1(_: []const u8) void {
-        debug.print("hello from day01 - part 1", .{});
+    pub fn part1(data: []const u8) i32 {
+        var iter = std.mem.splitAny(u8, data, "\n");
+        var count: i32 = 0;
+        var current: i32 = 50;
+
+        while (iter.next()) |line| {
+            const value = std.fmt.parseInt(i32, line[1..], 10) catch 0;
+            if (line[0] == 'L') {
+                current = @mod(current - value, 100);
+            } else {
+                current = @mod(current + value, 100);
+            }
+
+            if (current == 0) {
+                count += 1;
+            }
+
+            //debug.print("{s} -> {d} (count: {d})\n", .{ line, current, count });
+        }
+
+        return count;
     }
-    pub fn part2(_: []const u8) void {
-        debug.print("hello from day01 - part 2", .{});
+    pub fn part2(data: []const u8) i32 {
+        var iter = std.mem.splitAny(u8, data, "\n");
+        var count: i32 = 0;
+        var current: i32 = 50;
+
+        var new_current: i32 = 0;
+        var div: u32 = 0;
+        var nb_rotation: i32 = 0;
+
+        while (iter.next()) |line| {
+            var value = std.fmt.parseInt(i32, line[1..], 10) catch 0;
+            if (line[0] == 'L') {
+                value = -value;
+            }
+
+            new_current = current + value;
+            div = @divTrunc(@abs(new_current), 100);
+            nb_rotation = @as(i32, @intCast(div));
+            if (new_current < 0) {
+                if (current != 0)
+                    nb_rotation += 1;
+                new_current += 100 * nb_rotation;
+            } else {
+                if (new_current > 0) {
+                    new_current -= 100 * nb_rotation;
+                } else nb_rotation = 1;
+            }
+            new_current = @mod(new_current, 100);
+
+            //debug.print("{s} -> {d} (count: {d})\n", .{ line, current, count });
+            current = new_current;
+            count += nb_rotation;
+        }
+
+        return count;
     }
 };
+
+test "day 01 part 1" {
+    const test_input = "L68\nL30\nR48\nL5\nR60\nL55\nL1\nL99\nR14\nL82";
+    try expectEqual(Day.part1(test_input), 3);
+}
+test "day 01 part 2" {
+    const test_input = "L68\nL30\nR48\nL5\nR60\nL55\nL1\nL99\nR14\nL82";
+    try expectEqual(Day.part2(test_input), 6);
+}
+
+test "test_custom_2_1" {
+    return expectEqual(Day.part2("R48\nL498"), 5);
+}
+
+test "test_custom_2_2" {
+    try expectEqual(Day.part2("R1000"), 10);
+}
diff --git a/zig/src/main.zig b/zig/src/main.zig
index 854189a..28f9e86 100644
--- a/zig/src/main.zig
+++ b/zig/src/main.zig
@@ -7,6 +7,10 @@ const import_days = struct {
     pub const day01 = @import("days/day01.zig");
 };
 
+test {
+    std.testing.refAllDecls(@This());
+}
+
 pub fn main() !void {
     var gpa = std.heap.GeneralPurposeAllocator(.{}){};
     defer _ = gpa.deinit();
@@ -20,21 +24,23 @@ pub fn main() !void {
     var days = Map.init(alloc);
     defer days.deinit();
 
-    debug.print("Running day {d}\n", .{arg_day_nb});
     inline for (comptime std.meta.declarations(import_days)) |decl| {
         const day_str = decl.name[3..]; // Skip "day" prefix
         const day_number = try std.fmt.parseInt(usize, day_str, 10);
 
         if (day_number == arg_day_nb) {
+            debug.print("Running day {d}\n", .{arg_day_nb});
             const imported_day = @field(import_days, decl.name).Day;
             const day = Day{ .nb = imported_day.nb, .part1 = imported_day.part1, .part2 = imported_day.part2 };
 
             // TODO: get the correct input values
             const buffer = "coucou";
-            day.part1(buffer);
-            day.part2(buffer);
+            _ = day.part1(buffer);
+            _ = day.part2(buffer);
 
             break;
         }
+    } else {
+        debug.print("Could not find implementation for day {d}\n", .{arg_day_nb});
     }
 }
diff --git a/zig/src/utils/day.zig b/zig/src/utils/day.zig
index 0c021fa..efbe9e4 100644
--- a/zig/src/utils/day.zig
+++ b/zig/src/utils/day.zig
@@ -1,6 +1,6 @@
 const std = @import("std");
 
-const fn_part_run = *const fn (str_buffer: []const u8) void;
+const fn_part_run = *const fn (str_buffer: []const u8) i32;
 pub const Day = struct {
     nb: u32 = 0,
     part1: fn_part_run,