Solve day 10

src/day10.zig

@@ -0,0 +1,93 @@
+const std = @import("std");
+
+pub const input = @embedFile("input/day10.txt");
+const test_input1 = @embedFile("input/day10_test1.txt");
+const test_input2 = @embedFile("input/day10_test2.txt");
+
+var gpa = std.heap.GeneralPurposeAllocator(.{ .safety = true }){};
+const allocator = gpa.allocator();
+
+fn signal_strength(cycle: usize, x: isize) isize {
+    if (cycle == 20 or cycle == 60 or cycle == 100 or cycle == 140 or cycle == 180 or cycle == 220) {
+        return @intCast(isize, cycle) * x;
+    } else {
+        return 0;
+    }
+}
+
+pub fn solve_part1(data: []const u8) !isize {
+    var lines = std.mem.tokenize(u8, data, "\n");
+    var x: isize = 1;
+    var cycle: usize = 0;
+    var sum: isize = 0;
+    while (lines.next()) |line| {
+        if (std.mem.eql(u8, line, "noop")) {
+            cycle += 1;
+            sum += signal_strength(cycle, x);
+        } else {
+            var delta = try std.fmt.parseInt(isize, line[5..], 10);
+            cycle += 1;
+            sum += signal_strength(cycle, x);
+            cycle += 1;
+            sum += signal_strength(cycle, x);
+            x += delta;
+        }
+    }
+    return sum;
+}
+
+fn emit_ray(cycle: usize, x: isize, crt: *[6][40]bool) void {
+    if (x >= @mod(@intCast(isize, cycle), 40) - 1 and x <= (cycle % 40) + 1) {
+        crt[cycle / 40][cycle % 40] = true;
+    }
+}
+
+fn print_screen(crt: [6][40]bool) [246]u8 {
+    var screen = [_]u8{'.'} ** (6 * 41);
+    var row: usize = 0;
+    while (row < 6) : (row += 1) {
+        var col: usize = 0;
+        while (col < 40) : (col += 1) {
+            screen[(row * 41) + col] = if (crt[row][col]) '#' else '.';
+        }
+        screen[(row * 41) + col] = '\n';
+    }
+    return screen;
+}
+
+pub fn solve_part2(data: []const u8) ![246]u8 {
+    var lines = std.mem.tokenize(u8, data, "\n");
+    var x: isize = 1;
+    var cycle: usize = 0;
+    var crt = [_][40]bool{[_]bool{false} ** 40} ** 6;
+    while (lines.next()) |line| {
+        emit_ray(cycle, x, &crt);
+        if (std.mem.eql(u8, line, "noop")) {
+            cycle += 1;
+        } else {
+            var delta = try std.fmt.parseInt(isize, line[5..], 10);
+            cycle += 1;
+            emit_ray(cycle, x, &crt);
+            cycle += 1;
+            x += delta;
+            emit_ray(cycle, x, &crt);
+        }
+    }
+    return print_screen(crt);
+}
+
+test "solves part1" {
+    try std.testing.expectEqual(solve_part1(test_input2), 13140);
+}
+
+test "solves part2" {
+    try std.testing.expectEqualStrings(&try solve_part2(test_input2),
+        \\##..##..##..##..##..##..##..##..##..##..
+        \\###...###...###...###...###...###...###.
+        \\####....####....####....####....####....
+        \\#####.....#####.....#####.....#####.....
+        \\######......######......######......####
+        \\#######.......#######.......#######.....
+        \\
+    );
+}

src/input/day10.txt

@@ -0,0 +1,145 @@
+addx 1
+noop
+noop
+addx 4
+addx 5
+addx -2
+addx 19
+addx -12
+addx 3
+addx -2
+addx 4
+noop
+noop
+noop
+addx 3
+addx -8
+addx 15
+addx 1
+noop
+noop
+addx 6
+addx -1
+noop
+addx -38
+noop
+addx 10
+addx -5
+noop
+addx 3
+addx 2
+addx 7
+noop
+noop
+addx 3
+noop
+addx 2
+addx 3
+addx -2
+addx 2
+addx 7
+noop
+noop
+addx 9
+noop
+addx -12
+noop
+addx 11
+addx -38
+noop
+noop
+noop
+addx 5
+addx 5
+noop
+noop
+noop
+addx 3
+addx -12
+addx 14
+noop
+addx 1
+addx 3
+addx 1
+addx 5
+addx 4
+addx 1
+noop
+noop
+noop
+noop
+noop
+addx -9
+addx 17
+addx -39
+addx 38
+addx -8
+addx -26
+addx 3
+addx 4
+addx 16
+noop
+addx -11
+addx 3
+noop
+addx 2
+addx 3
+addx -2
+addx 2
+noop
+addx 13
+addx -8
+noop
+addx 7
+addx -5
+addx 8
+addx -40
+addx 16
+addx -9
+noop
+addx -7
+addx 8
+addx 2
+addx 7
+noop
+noop
+addx -15
+addx 16
+addx 2
+addx 5
+addx 2
+addx -20
+addx 12
+addx 11
+addx 8
+addx -1
+addx 3
+noop
+addx -39
+addx 2
+noop
+addx 5
+noop
+noop
+noop
+addx 4
+addx 1
+noop
+noop
+addx 2
+addx 5
+addx 2
+addx 1
+addx 4
+addx -1
+addx 2
+noop
+addx 2
+noop
+addx 8
+noop
+noop
+noop
+addx -10
+noop
+noop

src/input/day10_test1.txt

@@ -0,0 +1,3 @@
+noop
+addx 3
+addx -5

src/input/day10_test2.txt

@@ -0,0 +1,146 @@
+addx 15
+addx -11
+addx 6
+addx -3
+addx 5
+addx -1
+addx -8
+addx 13
+addx 4
+noop
+addx -1
+addx 5
+addx -1
+addx 5
+addx -1
+addx 5
+addx -1
+addx 5
+addx -1
+addx -35
+addx 1
+addx 24
+addx -19
+addx 1
+addx 16
+addx -11
+noop
+noop
+addx 21
+addx -15
+noop
+noop
+addx -3
+addx 9
+addx 1
+addx -3
+addx 8
+addx 1
+addx 5
+noop
+noop
+noop
+noop
+noop
+addx -36
+noop
+addx 1
+addx 7
+noop
+noop
+noop
+addx 2
+addx 6
+noop
+noop
+noop
+noop
+noop
+addx 1
+noop
+noop
+addx 7
+addx 1
+noop
+addx -13
+addx 13
+addx 7
+noop
+addx 1
+addx -33
+noop
+noop
+noop
+addx 2
+noop
+noop
+noop
+addx 8
+noop
+addx -1
+addx 2
+addx 1
+noop
+addx 17
+addx -9
+addx 1
+addx 1
+addx -3
+addx 11
+noop
+noop
+addx 1
+noop
+addx 1
+noop
+noop
+addx -13
+addx -19
+addx 1
+addx 3
+addx 26
+addx -30
+addx 12
+addx -1
+addx 3
+addx 1
+noop
+noop
+noop
+addx -9
+addx 18
+addx 1
+addx 2
+noop
+noop
+addx 9
+noop
+noop
+noop
+addx -1
+addx 2
+addx -37
+addx 1
+addx 3
+noop
+addx 15
+addx -21
+addx 22
+addx -6
+addx 1
+noop
+addx 2
+addx 1
+noop
+addx -10
+noop
+noop
+addx 20
+addx 1
+addx 2
+addx 2
+addx -6
+addx -11
+noop
+noop
+noop

src/main.zig

@@ -9,6 +9,7 @@ const day06 = @import("day06.zig");
 const day07 = @import("day07.zig");
 const day08 = @import("day08.zig");
 const day09 = @import("day09.zig");
+const day10 = @import("day10.zig");
 const utils = @import("utils.zig");
 
 fn solve_day(comptime day_num: u8, day: anytype, stdout: anytype, timer: *std.time.Timer) !void {
@@ -18,20 +19,20 @@ fn solve_day(comptime day_num: u8, day: anytype, stdout: anytype, timer: *std.ti
     var part1 = try day.solve_part1(day.input);
     const part1_end = timer.read();
     const part1_time = utils.HumanTime.new(part1_end - part1_start);
-    if (@TypeOf(part1) == []const u8) {
+    if (@TypeOf(part1) == usize or @TypeOf(part1) == isize) {
-        try stdout.print("Part 1: {s} ({d:.2} {s})\n", .{ part1, part1_time.value, part1_time.unit.abbr() });
-    } else {
         try stdout.print("Part 1: {} ({d:.2} {s})\n", .{ part1, part1_time.value, part1_time.unit.abbr() });
+    } else {
+        try stdout.print("Part 1: \n{s} ({d:.2} {s})\n", .{ part1, part1_time.value, part1_time.unit.abbr() });
     }
 
     const part2_start = timer.read();
     var part2 = try day.solve_part2(day.input);
     const part2_end = timer.read();
     const part2_time = utils.HumanTime.new(part2_end - part2_start);
-    if (@TypeOf(part2) == []const u8) {
+    if (@TypeOf(part2) == usize or @TypeOf(part2) == isize) {
-        try stdout.print("Part 2: {s} ({d:.2} {s})\n", .{ part2, part2_time.value, part2_time.unit.abbr() });
-    } else {
         try stdout.print("Part 2: {} ({d:.2} {s})\n", .{ part2, part2_time.value, part2_time.unit.abbr() });
+    } else {
+        try stdout.print("Part 2: \n{s} ({d:.2} {s})\n", .{ part2, part2_time.value, part2_time.unit.abbr() });
     }
 }
 
@@ -50,6 +51,7 @@ pub fn main() !void {
     try solve_day(7, day07, &stdout, &timer);
     try solve_day(8, day08, &stdout, &timer);
     try solve_day(9, day09, &stdout, &timer);
+    try solve_day(10, day10, &stdout, &timer);
 
     try bw.flush();
 }
@@ -66,5 +68,6 @@ test {
     _ = day07;
     _ = day08;
     _ = day09;
+    _ = day10;
     _ = utils;
 }