solve day 14
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@ -195,7 +195,7 @@ pub fn part2(input: *aoc.Input) !aoc.Result {
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return .{ .uint = sum_min_distances(galaxies.items) };
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}
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const example_input = [_][]u8{
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const example_input = [_][]const u8{
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"...#......",
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".......#..",
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"#.........",
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@ -208,7 +208,7 @@ pub fn part2(input: *aoc.Input) !aoc.Result {
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return .{ .uint = result };
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}
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const example_input = &.{
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const example_input = [_][]const u8{
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"#.##..##.",
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"..#.##.#.",
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"##......#",
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233
src/day14.zig
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233
src/day14.zig
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@ -0,0 +1,233 @@
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const std = @import("std");
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const aoc = @import("./aoc.zig");
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const assert = std.debug.assert;
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const Allocator = std.mem.Allocator;
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const PointU32 = @import("./point.zig").Point(u32);
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const Tile = enum {
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Empty,
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Rock,
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Wall
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};
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const Input = struct {
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tiles: std.ArrayList(Tile),
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width: u32,
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height: u32,
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fn init(allocator: Allocator) Input {
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return Input{
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.tiles = std.ArrayList(Tile).init(allocator),
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.width = 0,
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.height = 0,
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};
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}
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fn deinit(self: Input) void {
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self.tiles.deinit();
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}
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fn get_idx(self: Input, x: u32, y: u32) usize {
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assert(x < self.width);
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assert(y < self.height);
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return y * self.width + x;
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}
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fn get(self: Input, x: u32, y: u32) Tile {
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return self.tiles.items[self.get_idx(x, y)];
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}
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fn set(self: Input, x: u32, y: u32, tile: Tile) void {
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self.tiles.items[self.get_idx(x, y)] = tile;
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}
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fn in_bounds(self: Input, x: i32, y: i32) bool {
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return (0 <= x and x < self.width) and (0 <= y and y < self.height);
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}
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fn print(self: Input) void {
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for (0..self.height) |y| {
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for (0..self.height) |x| {
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const idx = y * self.width + x;
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const tile = self.tiles.items[idx];
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const symbol: u8 = switch (tile) {
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.Empty => '.',
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.Wall => '#',
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.Rock => 'O'
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};
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std.debug.print("{c}", .{symbol});
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}
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std.debug.print("\n", .{});
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}
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}
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};
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fn parse_input(allocator: Allocator, lines: []const []const u8) !Input {
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var parsed = Input.init(allocator);
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errdefer parsed.deinit();
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parsed.width = @intCast(lines[0].len);
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parsed.height = @intCast(lines.len);
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try parsed.tiles.ensureTotalCapacity(parsed.width * parsed.height);
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for (lines) |line| {
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for (line) |symbol| {
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const tile = switch (symbol) {
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'O' => Tile.Rock,
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'.' => Tile.Empty,
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'#' => Tile.Wall,
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else => return error.InvalidTile
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};
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try parsed.tiles.append(tile);
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}
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}
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return parsed;
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}
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fn slide_rock(input: Input, x: u32, y: u32, dir_x: i32, dir_y: i32) void {
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assert(input.get(x, y) == .Rock);
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var new_x = x;
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var new_y = y;
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while (true) {
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const next_x = @as(i32, @intCast(new_x)) + dir_x;
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const next_y = @as(i32, @intCast(new_y)) + dir_y;
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if (!input.in_bounds(next_x, next_y)) break;
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if (input.get(@intCast(next_x), @intCast(next_y)) != .Empty) break;
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new_x = @intCast(next_x);
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new_y = @intCast(next_y);
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}
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input.set(x, y, .Empty);
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input.set(new_x, new_y, .Rock);
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}
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fn slide_rocks(input: Input, dir_x: i32, dir_y: i32) void {
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if (dir_y != 0) {
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// Column-based
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for (0..input.height) |oy| {
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for (0..input.width) |ox| {
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const x: u32 = @intCast(ox);
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const y: u32 = @intCast(@as(i32, @intCast(oy)) * (-dir_y) + @divExact(dir_y + 1, 2) * @as(i32, @intCast(input.height-1)));
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if (input.get(x, y) == .Rock) {
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slide_rock(input, x, y, dir_x, dir_y);
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}
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}
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}
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} else {
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// Row-based
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for (0..input.width) |ox| {
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for (0..input.height) |oy| {
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const x: u32 = @intCast(@as(i32, @intCast(ox)) * (-dir_x) + @divExact(dir_x + 1, 2) * @as(i32, @intCast(input.width-1)));
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const y: u32 = @intCast(oy);
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if (input.get(x, y) == .Rock) {
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slide_rock(input, x, y, dir_x, dir_y);
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}
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}
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}
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}
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}
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fn cycle_slide(input: Input) void {
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const dirs = &.{
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.{ .x = 0, .y = -1 }, // North
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.{ .x = -1, .y = 0 }, // West
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.{ .x = 0, .y = 1 }, // South
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.{ .x = 1, .y = 0 }, // East
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};
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inline for (dirs) |dir| {
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slide_rocks(input, dir.x, dir.y);
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}
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}
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fn get_total_load(input: Input) u64 {
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var result: u64 = 0;
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for (0..input.height) |y| {
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var count: u32 = 0;
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for (0..input.width) |x| {
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if (input.get(@intCast(x), @intCast(y)) == .Rock) {
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count += 1;
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}
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}
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result += count * (input.height - y);
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}
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return result;
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}
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pub fn part1(input: *aoc.Input) !aoc.Result {
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const parsed = try parse_input(input.allocator, input.lines);
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defer parsed.deinit();
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slide_rocks(parsed, 0, -1);
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return .{ .uint = get_total_load(parsed) };
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}
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pub fn part2(input: *aoc.Input) !aoc.Result {
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const target_cycle_count = 1000000000;
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const allocator = input.allocator;
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const parsed = try parse_input(allocator, input.lines);
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defer parsed.deinit();
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var seen = std.ArrayList(std.ArrayList(Tile)).init(allocator);
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defer {
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for (seen.items) |tiles| {
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tiles.deinit();
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}
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seen.deinit();
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}
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var cycle_size: u32 = 0;
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var cycle_start: u32 = 0;
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var iteration: u32 = 0;
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outer: while (true) {
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cycle_slide(parsed);
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for (0.., seen.items) |i, tiles| {
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if (std.mem.eql(Tile, tiles.items, parsed.tiles.items)) {
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cycle_start = @intCast(i);
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cycle_size = @intCast(iteration - i);
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break :outer;
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}
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}
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try seen.append(try parsed.tiles.clone());
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iteration += 1;
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}
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const skipped_map = Input{
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.tiles = seen.items[@mod((target_cycle_count-1) - cycle_start, cycle_size) + cycle_start],
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.width = parsed.width,
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.height = parsed.height
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};
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return .{ .uint = get_total_load(skipped_map) };
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}
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const example_input = [_][]const u8{
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"O....#....",
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"O.OO#....#",
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".....##...",
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"OO.#O....O",
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".O.....O#.",
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"O.#..O.#.#",
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"..O..#O..O",
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".......O..",
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"#....###..",
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"#OO..#....",
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};
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test "part 1 example" {
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try aoc.expectAnswerUInt(part1, 136, &example_input);
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}
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test "part 2 example" {
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try aoc.expectAnswerUInt(part2, 64, &example_input);
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}
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53
src/main.zig
53
src/main.zig
@ -21,19 +21,20 @@ fn create_day(comptime module: anytype) aoc.Day {
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}
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const Days = [_]aoc.Day{
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create_day(@import("day1.zig")),
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create_day(@import("day2.zig")),
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create_day(@import("day3.zig")),
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create_day(@import("day4.zig")),
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create_day(@import("day5.zig")),
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create_day(@import("day6.zig")),
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create_day(@import("day7.zig")),
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create_day(@import("day8.zig")),
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create_day(@import("day9.zig")),
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create_day(@import("day10.zig")),
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create_day(@import("day11.zig")),
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create_day(@import("day12.zig")),
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create_day(@import("day13.zig")),
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create_day(@import("./day1.zig")),
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create_day(@import("./day2.zig")),
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create_day(@import("./day3.zig")),
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create_day(@import("./day4.zig")),
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create_day(@import("./day5.zig")),
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create_day(@import("./day6.zig")),
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create_day(@import("./day7.zig")),
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create_day(@import("./day8.zig")),
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create_day(@import("./day9.zig")),
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create_day(@import("./day10.zig")),
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create_day(@import("./day11.zig")),
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create_day(@import("./day12.zig")),
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create_day(@import("./day13.zig")),
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create_day(@import("./day14.zig")),
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};
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fn kilobytes(count: u32) u32 {
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@ -178,16 +179,18 @@ pub fn main() !u8 {
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}
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test {
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_ = @import("day1.zig");
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_ = @import("day2.zig");
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_ = @import("day3.zig");
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_ = @import("day4.zig");
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_ = @import("day5.zig");
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_ = @import("day6.zig");
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_ = @import("day7.zig");
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_ = @import("day8.zig");
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_ = @import("day9.zig");
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_ = @import("day10.zig");
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_ = @import("day11.zig");
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_ = @import("day12.zig");
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_ = @import("./day1.zig");
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_ = @import("./day2.zig");
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_ = @import("./day3.zig");
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_ = @import("./day4.zig");
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_ = @import("./day5.zig");
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_ = @import("./day6.zig");
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_ = @import("./day7.zig");
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_ = @import("./day8.zig");
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_ = @import("./day9.zig");
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_ = @import("./day10.zig");
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_ = @import("./day11.zig");
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_ = @import("./day12.zig");
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_ = @import("./day13.zig");
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_ = @import("./day14.zig");
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}
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