AOC2021 Day 25

index.html

<h1 id="header">Advent of Code 2021 Day 25</h1>
<div id="wrapper">
  <canvas id="canvas" width="417" height="411"></canvas>
</div>
<p id='status'>Run me</p>

main.dart

import 'dart:html';
import 'dart:async';

extension IntToExt on int {
  to(int end, {int step = 1}) sync* {
    for (int i = this; i < end; i += step) {
      yield i;
    }
  }
}

extension IterMaxExt on Iterable<int> {
  int max() => reduce((s, t) => s > t ? s : t);
  int min() => reduce((s, t) => s < t ? s : t);
}

class Index {
  final int r;
  final int c;

  const Index(this.r, this.c);

  @override
  String toString() => 'Index($r, $c)';

  @override
  bool operator ==(Object other) =>
      other is Index && r == other.r && c == other.c;

  @override
  int get hashCode => Object.hash(r.hashCode, c.hashCode);

  Index operator +(Index other) => Index(r + other.r, c + other.c);
  Index operator -(Index other) => Index(r - other.r, c - other.c);
}

abstract class Grid<T> {
  static const n8 = [
    Index(-1, -1),
    Index(-1, 0),
    Index(-1, 1),
    Index(0, -1),
    Index(0, 1),
    Index(1, -1),
    Index(1, 0),
    Index(1, 1)
  ];
  // including self
  static const n9 = [
    Index(-1, -1),
    Index(-1, 0),
    Index(-1, 1),
    Index(0, -1),
    Index(0, 0),
    Index(0, 1),
    Index(1, -1),
    Index(1, 0),
    Index(1, 1)
  ];
  static const n4 = [Index(-1, 0), Index(1, 0), Index(0, -1), Index(0, 1)];

  int get width;
  int get height;

  T operator [](Index p);
  operator []=(Index p, T value);

  @override
  bool operator ==(Object other) =>
      other is Grid &&
      width == other.width &&
      height == other.height &&
      indexes.every((i) => this[i] == other[i]);

  @override
  int get hashCode => Object.hashAll(indexes.map((i) => this[i]));

  /// Useful enumeration for printing.
  List<T> row(int r);

  bool isInBounds(Index n) =>
      n.r >= 0 && n.r < height && n.c >= 0 && n.c < width;

  Iterable<Index> near8(Index p) => n8.map((e) => e + p).where(isInBounds);
  Iterable<Index> near4(Index p) => n4.map((e) => e + p).where(isInBounds);
  Iterable<Index> near9(Index p) => n9.map((e) => e + p).where(isInBounds);
  Iterable<Index> near9raw(Index p) => n9.map((e) => e + p);

  Index safe(Index i) => Index(i.r % height, i.c % width);

  /// Get all indexes in row, column order.
  Iterable<Index> get indexes sync* {
    for (int r in 0.to(height)) {
      for (int c in 0.to(width)) {
        yield Index(r, c);
      }
    }
  }
}

class ListGrid<T> extends Grid<T> {
  late final List<List<T>> _list;
  ListGrid(List<List<T>> list) : _list = list;
  ListGrid.ofSize(rows, columns, T value)
      : _list = List.generate(
            rows, (index) => List.generate(columns, (index) => value));
  ListGrid.copyFrom(ListGrid<T> grid)
      : _list = List.generate(grid.height,
            (r) => List.generate(grid.width, (c) => grid[Index(r, c)]));
  @override
  int get width => _list.first.length;
  @override
  int get height => _list.length;

  put(Index p, T value) => _list[p.r][p.c] = value;
  T at(Index p) => _list[p.r][p.c];
  @override
  T operator [](Index p) => _list[p.r][p.c];
  @override
  operator []=(Index p, T value) => _list[p.r][p.c] = value;

  @override
  List<T> row(int r) => _list[r];
  // ignore: avoid_function_literals_in_foreach_calls
  printIt() => _list.forEach((e) => print(e.join()));
}

late ListGrid<String> grid;

buildGrid(List<String> lines) {
  grid = ListGrid<String>(lines.map((e) => e.split('')).toList());
}

stepsUntilComplete(dynamic callback) {
  var i = 0;
  while (true) {
    if (i == 10) break;
    i += 1;
    var oldGrid = ListGrid.copyFrom(grid);
    step();
    callback(i);
    if (keyboard.isPressed(KeyCode.SPACE)) break;
    if (grid == oldGrid) break;
  }
  return i;
}

step() {
  var newGrid = ListGrid.copyFrom(grid);
  // eastward first
  for (var i in grid.indexes) {
    if (grid[i] == '>') {
      var n = grid.safe(Index(i.r, i.c + 1));
      if (grid[n] == '.') {
        newGrid[i] = '.';
        newGrid[n] = '>';
      }
    }
  }
  grid = newGrid;
  newGrid = ListGrid.copyFrom(grid);
  // southward
  for (var i in grid.indexes) {
    if (grid[i] == 'v') {
      var n = grid.safe(Index(i.r + 1, i.c));
      if (grid[n] == '.') {
        newGrid[i] = '.';
        newGrid[n] = 'v';
      }
    }
  }
  grid = newGrid;
}

var data =
    '''vv>...v>......>>vv>.v.>>.v.vvv..>..>.v...v...>...vv..>v>..>.>>.>>...v>.v.v>..>>>>vv...vv..v>.v>.>v...>>..vv>v>vv..>>.>..v>>..v.vv..>.vv>..v
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class Keyboard {
  final _keys = <int, num>{};

  Keyboard() {
    window.onKeyDown.listen((KeyboardEvent event) {
      _keys.putIfAbsent(event.keyCode, () => event.timeStamp!);
    });

    window.onKeyUp.listen((KeyboardEvent event) {
      _keys.remove(event.keyCode);
    });
  }

  bool isPressed(int keyCode) => _keys.containsKey(keyCode);
}

const int cellSize = 3;
late CanvasElement canvas;
late CanvasRenderingContext2D ctx;
Keyboard keyboard = Keyboard();

renderGrid(int i) {
  ctx.fillStyle = 'darkgrey';
  ctx.fillRect(0, 0, canvas.width!, canvas.height!);
  for (var i in grid.indexes) {
    var x = i.c * cellSize;
    var y = i.r * cellSize;
    var color =
        grid[i] == '>' ? 'darkgreen' : (
          grid[i] == 'v' ? 'green' : 'darkgrey');
  ctx
    ..fillStyle = color
    ..strokeStyle = color
    ..fillRect(x, y, cellSize, cellSize)
    ..strokeRect(x, y, cellSize, cellSize);
  }
    querySelector('#status')!.text = 'Step number $i';
}

var stepNo = 0;
late Timer timer;
drawAndStepUntilComplete(dynamic callback) {
    stepNo += 1;
    var oldGrid = ListGrid.copyFrom(grid);
    step();
    callback(stepNo);
//    if (stepNo == 10) timer.cancel();
    if (keyboard.isPressed(KeyCode.SPACE)) timer.cancel();
    if (grid == oldGrid) timer.cancel();

}

main() {
  var t = DateTime.now();
  canvas = querySelector('#canvas')! as CanvasElement;
  ctx = canvas.getContext('2d') as CanvasRenderingContext2D;
  ctx.fillStyle = 'darkgrey';
  ctx.fillRect(0, 0, canvas.width!, canvas.height!);
  var lines = data.split('\n');
  print(lines.length);
  print(lines.first.length);
  buildGrid(lines);
  timer = Timer.periodic(Duration(milliseconds:30),(timer)=>drawAndStepUntilComplete(renderGrid));
  print('${DateTime.now().difference(t).inMilliseconds} milliseconds');
}

styles.css

body {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  position: absolute;
  width: 100%;
  height: 100%;
}

* {
  color: white;
  font-family: Arial, Helvetica, sans-serif;
}