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// needs -O ReleaseFast, else super slow
const std = @import("std");
const data = @embedFile("day14");
var area = [_][800]u8{ [_]u8{0} ** 800 } ** 800;
fn draw(ox: usize, oy: usize, x: usize, y: usize) void {
if (ox == x) {
var vy = std.math.min(oy, y);
while (vy <= std.math.max(oy, y)) : (vy += 1)
area[x][vy] = 9;
} else {
var vx = std.math.min(ox, x);
while (vx <= std.math.max(ox, x)) : (vx += 1)
area[vx][y] = 9;
}
}
fn drop_sand(y1: usize, x1: usize) bool {
var y = y1;
var x = x1;
while (x < 799 and y < 799) {
if (area[y+1][x] == 0) {
y += 1;
continue;
}
if (area[y+1][x-1] == 0) {
x -= 1;
y += 1;
continue;
}
if (area[y+1][x+1] == 0) {
x += 1;
y += 1;
continue;
}
area[y][x] = 1;
return true;
}
return false;
}
pub fn main() !void {
var lines = std.mem.tokenize(u8, data, "\n");
while (lines.next()) |line| {
if (line.len == 0)
break;
var coords = std.mem.tokenize(u8, line, " -> ");
var ox: usize = 0;
var oy: usize = 0;
while (coords.next()) |coord| {
var ns = std.mem.tokenize(u8, coord, ",");
var y = try std.fmt.parseInt(usize, ns.next().?, 10);
var x = try std.fmt.parseInt(usize, ns.next().?, 10);
if (ox != 0)
draw(ox, oy, x, y);
ox = x;
oy = y;
}
}
var part1: usize = 0;
while (drop_sand(0, 500))
part1 += 1;
for (area) |*line| {
for (line) |*item| {
if (item.* == 1)
item.* = 0;
}
}
var bottom: usize = 799;
loop: while (bottom > 0) : (bottom -= 1) {
for (area[bottom]) |item| {
if (item == 9) {
draw(bottom + 2, 0, bottom + 2, 799);
break :loop;
}
}
}
var part2: usize = 0;
loop: while (drop_sand(0, 500)) {
part2 += 1;
if (area[0][500] != 0)
break :loop;
}
// for (area) |line| {
// for (line) |item| {
// std.debug.print("{}", .{item});
// }
// std.debug.print("\n", .{});
// }
std.debug.print("{}\n{}\n", .{part1, part2});
}
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