30:Tadf,energized = { const UP = 1 << 0, DOWN = 1 << 1, LEFT = 1 << 2, RIGHT = 1 << 3; const V = new Float32Array((W + 1) * (W + 1)).fill(0); // initialize const energized = new Set([0]); V[0] |= RIGHT; let s; do { for (const e of energized) { if (V[e] & RIGHT) { switch (input[e]) { case ".": case "-": V[e + 1] |= RIGHT; energized.add(e + 1); break; case "|": V[e - (W + 1)] |= UP; V[e + (W + 1)] |= DOWN; energized.add(e - (W + 1)); energized.add(e + (W + 1)); break; case "\\": V[e + (W + 1)] |= DOWN; energized.add(e + (W + 1)); break; case "/": V[e - (W + 1)] |= UP; energized.add(e - (W + 1)); break; } } if (V[e] & LEFT) { switch (input[e]) { case ".": case "-": V[e - 1] |= LEFT; energized.add(e - 1); break; case "|": V[e - (W + 1)] |= UP; V[e + (W + 1)] |= DOWN; energized.add(e - (W + 1)); energized.add(e + (W + 1)); break; case "/": V[e + (W + 1)] |= DOWN; energized.add(e + (W + 1)); break; case "\\": V[e - (W + 1)] |= UP; energized.add(e - (W + 1)); break; } } if (V[e] & UP) { switch (input[e]) { case ".": case "|": V[e - (W + 1)] |= UP; energized.add(e - (W + 1)); break; case "-": V[e - 1] |= LEFT; V[e + 1] |= RIGHT; energized.add(e - 1); energized.add(e + 1); break; case "/": V[e + 1] |= RIGHT; energized.add(e + 1); break; case "\\": V[e - 1] |= LEFT; energized.add(e - 1); break; } } if (V[e] & DOWN) { switch (input[e]) { case ".": case "|": V[e + (W + 1)] |= DOWN; energized.add(e + (W + 1)); break; case "-": V[e - 1] |= LEFT; V[e + 1] |= RIGHT; energized.add(e - 1); energized.add(e + 1); break; case "\\": V[e + 1] |= RIGHT; energized.add(e + 1); break; case "/": V[e - 1] |= LEFT; energized.add(e - 1); break; } } } yield energized; const s0 = d3.sum(V); if (s0 === s) break; s = s0; } while (true); yield energized; }31:Te1e,energized2 = { await visibility(); const UP = 1 << 0, DOWN = 1 << 1, LEFT = 1 << 2, RIGHT = 1 << 3; const V = new Float32Array((W + 1) * (W + 1)); const COUNTS = []; const valid = (d) => !(d < 0 || d >= W * (W + 1) || (1 + d) % (W + 1) === 0); // for the display mutable best = count(W - 1 + 93 * (W + 1), LEFT); for (let i = 0; i < W; ++i) { // TOP COUNTS.push([...count(i, DOWN)].filter(valid).length); // LEFT COUNTS.push([...count(i * (W + 1), RIGHT)].filter(valid).length); // BOTTOM COUNTS.push([...count(i + (W - 1) * (W + 1), UP)].filter(valid).length); // RIGHT COUNTS.push([...count(W - 1 + i * (W + 1), LEFT)].filter(valid).length); yield COUNTS; } return COUNTS; function count(i, dir) { // initialize V.fill(0); const energized = new Set([i]); V[i] |= dir; let s; do { for (const e of energized) { if (V[e] & RIGHT) { switch (input[e]) { case ".": case "-": V[e + 1] |= RIGHT; energized.add(e + 1); break; case "|": V[e - (W + 1)] |= UP; V[e + (W + 1)] |= DOWN; energized.add(e - (W + 1)); energized.add(e + (W + 1)); break; case "\\": V[e + (W + 1)] |= DOWN; energized.add(e + (W + 1)); break; case "/": V[e - (W + 1)] |= UP; energized.add(e - (W + 1)); break; } } if (V[e] & LEFT) { switch (input[e]) { case ".": case "-": V[e - 1] |= LEFT; energized.add(e - 1); break; case "|": V[e - (W + 1)] |= UP; V[e + (W + 1)] |= DOWN; energized.add(e - (W + 1)); energized.add(e + (W + 1)); break; case "/": V[e + (W + 1)] |= DOWN; energized.add(e + (W + 1)); break; case "\\": V[e - (W + 1)] |= UP; energized.add(e - (W + 1)); break; } } if (V[e] & UP) { switch (input[e]) { case ".": case "|": V[e - (W + 1)] |= UP; energized.add(e - (W + 1)); break; case "-": V[e - 1] |= LEFT; V[e + 1] |= RIGHT; energized.add(e - 1); energized.add(e + 1); break; case "/": V[e + 1] |= RIGHT; energized.add(e + 1); break; case "\\": V[e - 1] |= LEFT; energized.add(e - 1); break; } } if (V[e] & DOWN) { switch (input[e]) { case ".": case "|": V[e + (W + 1)] |= DOWN; energized.add(e + (W + 1)); break; case "-": V[e - 1] |= LEFT; V[e + 1] |= RIGHT; energized.add(e - 1); energized.add(e + 1); break; case "\\": V[e + 1] |= RIGHT; energized.add(e + 1); break; case "/": V[e - 1] |= LEFT; energized.add(e - 1); break; } } } const s0 = d3.sum(V); if (s0 === s) break; s = s0; } while (true); return energized; } }32:[{"id":"4d3b0c176b94777753d00683fd48960c1fadf1ec60db4b866ca40862d45c190ff5101fbe0301e42e6e7013d04da6ff6be40bdb42a527894a17a68a34b4371dfa","href":"https://static.observableusercontent.com/files/4d3b0c176b94777753d00683fd48960c1fadf1ec60db4b866ca40862d45c190ff5101fbe0301e42e6e7013d04da6ff6be40bdb42a527894a17a68a34b4371dfa","name":"input.txt","type":"text/plain","lastModified":1702825035520.182,"size":12210}] 2e:{"title":"Advent of Code 2023 - #16","cells":[{"id":0,"value":"# Advent of Code 2023 - #16\n\nhttps://adventofcode.com/2023/day/16","pinned":false,"hidden":false,"mode":"md"},{"id":11,"value":"show(input, energized)","pinned":true,"hidden":false,"mode":"ojs"},{"id":114,"value":"answer1 = [...energized].filter(\n (d) => !(d < 0 || d >= W * (W + 1) || (1 + d) % (W + 1) === 0)\n).length","pinned":true,"hidden":false,"mode":"ojs"},{"id":50,"value":"W = input.trim().split(\"\\n\").length","pinned":true,"hidden":false,"mode":"ojs"},{"id":51,"value":"$30","pinned":true,"hidden":false,"mode":"ojs"},{"id":137,"value":"---\n## Part 2","pinned":false,"hidden":false,"mode":"md"},{"id":191,"value":"show(input, best, 93)","pinned":false,"hidden":false,"mode":"ojs"},{"id":141,"value":"$31","pinned":true,"hidden":false,"mode":"ojs"},{"id":151,"value":"l = d3.maxIndex(energized2)","pinned":true,"hidden":false,"mode":"ojs"},{"id":164,"value":"answer2 = energized2[l]","pinned":true,"hidden":false,"mode":"ojs"},{"id":180,"value":"*out of curiosity, which one is that?*","pinned":false,"hidden":false,"mode":"md"},{"id":176,"value":"m = l % 4 // RIGHT","pinned":true,"hidden":false,"mode":"ojs"},{"id":169,"value":"i = Math.floor(l / 4)","pinned":true,"hidden":false,"mode":"ojs"},{"id":185,"value":"mutable best = null","pinned":true,"hidden":false,"mode":"ojs"},{"id":3,"value":"input = FileAttachment(\"input.txt\").text() // beware of escaping \\","pinned":false,"hidden":true,"mode":"ojs"},{"id":122,"value":"sample = `.|...\\\\....\n|.-.\\\\.....\n.....|-...\n........|.\n..........\n.........\\\\\n..../.\\\\\\\\..\n.-.-/..|..\n.|....-|.\\\\\n..//.|....\n`","pinned":true,"hidden":false,"mode":"ojs"},{"id":9,"value":"show = (txt, energized, startRight) =>\n html`

${Array.from(txt, (d, i) => {\n    const a = (i + 1) % (W + 1) === 0 ? \"◼\\n\" : d;\n    return i === startRight * (W + 1) + W\n      ? html`${a}`\n      : energized?.has(i)\n      ? html`${a}`\n      : a;\n  })}

`","pinned":true,"hidden":false,"mode":"ojs"}],"files":"$W32","stdlib":"1","titling":"auto"}