Day 14

1 year ago · 99988afbe7
2 changed files with 289 additions and 0 deletions
--- a/14/input
+++ b/14/input
@ -0,0 +1,118 @@
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+454,118 -> 454,122 -> 451,122 -> 451,126 -> 464,126 -> 464,122 -> 458,122 -> 458,118
+440,135 -> 440,136 -> 453,136 -> 453,135
+498,21 -> 502,21
+469,69 -> 473,69
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+489,19 -> 493,19
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+449,84 -> 453,84
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+438,158 -> 442,158
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+463,65 -> 467,65
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+472,67 -> 476,67
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+445,131 -> 454,131 -> 454,130
+452,86 -> 456,86
+455,88 -> 459,88
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+492,21 -> 496,21
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+466,67 -> 470,67
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+466,63 -> 470,63
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+486,21 -> 490,21
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+426,158 -> 430,158
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+441,111 -> 441,105 -> 441,111 -> 443,111 -> 443,104 -> 443,111 -> 445,111 -> 445,106 -> 445,111 -> 447,111 -> 447,104 -> 447,111
+441,114 -> 441,115 -> 455,115
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+475,69 -> 479,69
+435,149 -> 435,148 -> 435,149 -> 437,149 -> 437,146 -> 437,149 -> 439,149 -> 439,146 -> 439,149 -> 441,149 -> 441,145 -> 441,149
+454,118 -> 454,122 -> 451,122 -> 451,126 -> 464,126 -> 464,122 -> 458,122 -> 458,118
+463,69 -> 467,69
+432,158 -> 436,158
+439,91 -> 439,94 -> 435,94 -> 435,98 -> 444,98 -> 444,94 -> 443,94 -> 443,91
+454,118 -> 454,122 -> 451,122 -> 451,126 -> 464,126 -> 464,122 -> 458,122 -> 458,118
+439,91 -> 439,94 -> 435,94 -> 435,98 -> 444,98 -> 444,94 -> 443,94 -> 443,91
+435,149 -> 435,148 -> 435,149 -> 437,149 -> 437,146 -> 437,149 -> 439,149 -> 439,146 -> 439,149 -> 441,149 -> 441,145 -> 441,149
+432,152 -> 436,152
+439,91 -> 439,94 -> 435,94 -> 435,98 -> 444,98 -> 444,94 -> 443,94 -> 443,91
+435,149 -> 435,148 -> 435,149 -> 437,149 -> 437,146 -> 437,149 -> 439,149 -> 439,146 -> 439,149 -> 441,149 -> 441,145 -> 441,149
+473,47 -> 473,42 -> 473,47 -> 475,47 -> 475,45 -> 475,47 -> 477,47 -> 477,39 -> 477,47 -> 479,47 -> 479,45 -> 479,47 -> 481,47 -> 481,42 -> 481,47 -> 483,47 -> 483,46 -> 483,47 -> 485,47 -> 485,39 -> 485,47
+441,111 -> 441,105 -> 441,111 -> 443,111 -> 443,104 -> 443,111 -> 445,111 -> 445,106 -> 445,111 -> 447,111 -> 447,104 -> 447,111
+495,14 -> 506,14 -> 506,13
+435,149 -> 435,148 -> 435,149 -> 437,149 -> 437,146 -> 437,149 -> 439,149 -> 439,146 -> 439,149 -> 441,149 -> 441,145 -> 441,149
+449,88 -> 453,88
+441,111 -> 441,105 -> 441,111 -> 443,111 -> 443,104 -> 443,111 -> 445,111 -> 445,106 -> 445,111 -> 447,111 -> 447,104 -> 447,111
--- a/14/solution.mjs
+++ b/14/solution.mjs
@ -0,0 +1,171 @@
+import { readFileSync } from 'node:fs';
+
+const input = readFileSync('input', 'utf-8');
+
+function inclusiveRange(from, to) {
+  const difference = to - from;
+  const distance = Math.abs(difference);
+  const add = difference / (distance || 1);
+  return new Array(distance + 1).fill().map((_, i) => from + i * add)
+}
+
+const rockCoords = input
+  .split('\n')
+  .filter(Boolean)
+  .flatMap(path => path
+    .split(' -> ')
+    .map(coordinates => coordinates
+      .split(',')
+      .map(coordinate => parseInt(coordinate))
+    )
+    // Separate into pairs of coordinates that represent a line
+    .flatMap((coord, i, coords) => i === 0 ? [] : [[coords[i - 1], coord]])
+    // Fill in gaps between coordinates, will include duplicates
+    .flatMap(([from, to]) => [
+      ...inclusiveRange(from[0], to[0]).map(x => [x, from[1]]),
+      ...inclusiveRange(from[1], to[1]).map(y => [from[0], y])
+    ])
+  );
+
+class InfinitePage {
+  constructor() {
+    this.ox = null;
+    this.oy = null;
+    this.lines = [];
+  }
+
+  get(x, y) {
+    return this.lines[y - (this.oy ?? y)]?.[x - (this.ox ?? x)] || ' ';
+  }
+
+  set(x, y, v) {
+    const c = v?.length ? v[0] : ' ';
+
+    if (this.ox === null) this.ox = x;
+    if (this.oy === null) this.oy = y;
+
+    const height = this.lines.length;
+    const width = this.lines[0]?.length ?? 0;
+
+    const expandLeft = Math.max(0, this.ox - x);
+    const expandUp = Math.max(0, this.oy - y);
+    const expandRight = Math.max(0, (x - this.ox + 1) - width);
+    const expandDown = Math.max(0, (y - this.oy + 1) - height);
+
+    this.expand(expandUp, expandRight, expandDown, expandLeft);
+    
+    const ax = x - this.ox;
+    const ay = y - this.oy;
+
+    const line = this.lines[ay];
+    this.lines[ay] = line.slice(0, ax) + c + line.slice(ax + 1);
+  }
+
+  expand(up, right, down, left) {
+    const width = this.lines[0]?.length ?? 0;
+
+    if (up + right + down + left > 0) {
+      this.lines = [
+        ...new Array(up).fill(' '.repeat(width)),
+        ...this.lines,
+        ...new Array(down).fill(' '.repeat(width))
+      ].map(line => ' '.repeat(left) + line + ' '.repeat(right));
+    }
+
+    this.ox -= left;
+    this.oy -= up;
+  }
+
+  print() {
+    console.log(this.lines.join('\n'));
+  }
+
+  getBounds() {
+    return {
+      minX: this.ox,
+      maxX: this.ox + (this.lines[0]?.length ?? 1) - 1,
+      minY: this.oy,
+      maxY: this.oy + (this.lines.length || 1) - 1
+    };
+  }
+}
+
+function getCave() {
+  const cave = new InfinitePage();
+  for (const coord of rockCoords) {
+    cave.set(...coord, '#');
+  }
+  return cave;
+}
+
+// Sand simulation
+function nextSandPos(x, y, canMoveTo) {
+  const fallPriority = [
+    {x: 0, y: 1},
+    {x: -1, y: 1},
+    {x: 1, y: 1}
+  ];
+  for (const fall of fallPriority) {
+    const nx = x + fall.x;
+    const ny = y + fall.y;
+
+    if (canMoveTo(nx, ny)) {
+      return [nx, ny];
+    }
+  }
+}
+
+function addUnitOfSand(cave, canMoveTo) {
+  let x = 500;
+  let y = 0;
+  while (true) {
+    let nextPos = nextSandPos(x, y, canMoveTo);
+    if (!nextPos) {
+      cave.set(x, y, 'o');
+      break;
+    }
+    ([x, y] = nextPos);
+  }
+};
+
+class EndSimulationError extends Error {}
+function simulateSand(cave, canMoveTo) {
+  let sandCount = 0;
+  while (true) {
+    try {
+      addUnitOfSand(cave, canMoveTo);
+      sandCount++;
+    } catch (err) {
+      if (!(err instanceof EndSimulationError)) {
+        throw err;
+      }
+      break;
+    }
+  }
+  return sandCount;
+}
+
+const cave1 = getCave();
+const bounds = cave1.getBounds();
+const count1 = simulateSand(
+  cave1,
+  (x, y) => {
+    if (x < bounds.minX || x > bounds.maxX || y < 0 || y > bounds.maxY) {
+      throw new EndSimulationError();
+    }
+    return cave1.get(x, y) === ' ';
+  }
+);
+console.log(`First simulation ended after ${count1} units of sand`);
+
+const cave2 = getCave();
+const count2 = simulateSand(
+  cave2,
+  (x, y) => {
+    if (cave2.get(500, 0) === 'o') {
+      throw new EndSimulationError();
+    }
+    return y < bounds.maxY + 2 && cave2.get(x, y) === ' ';
+  }
+)
+console.log(`Second simulation ended after ${count2} units of sand`);