116 lines
2.9 KiB
Zig
116 lines
2.9 KiB
Zig
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const std = @import("std");
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const print = std.debug.print;
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const matrixSize = 10;
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const iterations = std.math.maxInt(u32);
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// const iterations = 100;
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// const iterations = 10;
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const Point = [2]usize;
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const NeighborList = struct {
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fn init(alloc: *std.mem.Allocator, x: usize, y: usize) std.ArrayList(Point) {
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var list = std.ArrayList(Point).init(alloc);
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for ([_]i8{-1, 0, 1}) |a| {
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var _x = @intCast(i8, x & 0xf) + a;
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if (_x < 0 or _x >= matrixSize) continue;
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for ([_]i8{-1, 0, 1}) |b| {
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var _y = @intCast(i8, y & 0xf) + b;
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if (_y < 0 or _y >= matrixSize) continue;
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if (a == 0 and b == 0) continue;
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list.append(Point{@intCast(usize, _x), @intCast(usize, _y)}) catch {};
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}
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}
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return list;
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}
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};
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pub fn main() !void {
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var alloc = std.heap.GeneralPurposeAllocator(.{}){};
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defer std.debug.assert(!alloc.deinit());
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var gpa = &alloc.allocator;
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const stdin = std.io.getStdIn().reader();
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var flashes: u32 = 0;
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var fullFlashStep: u32 = 0;
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var matrix: [matrixSize][matrixSize]u8 = undefined;
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// parse data
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{
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var tmp: [256]u8 = undefined;
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var i: u8 = 0;
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while (try stdin.readUntilDelimiterOrEof(&tmp, '\n')) |line| {
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for (line) |char, j| {
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matrix[i][j] = char - 0x30;
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}
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i += 1;
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}
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}
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var i: u32 = 0;
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while (i < iterations) : (i += 1) {
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// print("iteration {}\n", .{i});
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var flashed: [matrixSize][matrixSize]bool = undefined;
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for (matrix) |row, x| {
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for (row) |_, y| {
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matrix[x][y] += 1;
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}
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}
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while (true) {
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var retry = false;
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for (matrix) |row, x| {
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for (row) |tile, y| {
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if (matrix[x][y] > 9 and !flashed[x][y]) {
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flashed[x][y] = true;
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retry = true;
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if (i < 100) flashes += 1;
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var neigh = NeighborList.init(gpa, x, y);
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defer neigh.deinit();
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for (neigh.items) |point| {
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matrix[point[0]][point[1]] += 1;
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}
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}
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}
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}
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if (!retry) break;
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}
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var numFlashed: u8 = 0;
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for (flashed) |row, x| {
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for (row) |hasFlashed, y| {
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if (hasFlashed) {
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matrix[x][y] = 0;
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numFlashed += 1;
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}
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}
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}
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if (numFlashed == comptime matrixSize * matrixSize) {
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fullFlashStep = i + 1;
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break;
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}
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// for (matrix) |row| {
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// print("{any}\n", .{row});
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// }
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}
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print("{}\n", .{flashes});
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print("{}\n", .{fullFlashStep});
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}
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