Add day 16 of year 2024 🧝‍♀️

2024/days/day-16/README.md

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+# Benchmark
+
+```
+Platform: darwin arm64
+CPU: Apple M3 Pro 11 Cores
+Memory: 18.00 GB
+```
+
+## Sample 1
+
+| part | time (~) | μs                  |
+| ---- | -------- | ------------------- |
+| 1    | 0.41ms   | 0.40595799999999826 |
+| 2    | 1.96ms   | 1.9566669999999995  |
+
+## Sample 2
+
+| part | time (~) | μs                 |
+| ---- | -------- | ------------------ |
+| 1    | 0.27ms   | 0.2736249999999991 |
+| 2    | 0.56ms   | 0.5599999999999987 |
+
+## Answer
+
+| part | time (~) | μs          |
+| ---- | -------- | ----------- |
+| 1    | 10.97ms  | 10.974833   |
+| 2    | 8.328s   | 8327.917625 |

2024/days/day-16/in.sample.1.txt

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+###############
+#.......#....E#
+#.#.###.#.###.#
+#.....#.#...#.#
+#.###.#####.#.#
+#.#.#.......#.#
+#.#.#####.###.#
+#...........#.#
+###.#.#####.#.#
+#...#.....#.#.#
+#.#.#.###.#.#.#
+#.....#...#.#.#
+#.###.#.#.#.#.#
+#S..#.....#...#
+###############

2024/days/day-16/in.sample.2.txt

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+#################
+#...#...#...#..E#
+#.#.#.#.#.#.#.#.#
+#.#.#.#...#...#.#
+#.#.#.#.###.#.#.#
+#...#.#.#.....#.#
+#.#.#.#.#.#####.#
+#.#...#.#.#.....#
+#.#.#####.#.###.#
+#.#.#.......#...#
+#.#.###.#####.###
+#.#.#...#.....#.#
+#.#.#.#####.###.#
+#.#.#.........#.#
+#.#.#.#########.#
+#S#.............#
+#################

2024/days/day-16/main.js

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+const fs = require('fs');
+
+function parse(source) {
+  return source
+    .trim()
+    .split('\n')
+    .map((e) => e.split(''));
+}
+
+Array.prototype.sum = function () {
+  return this.reduce((sum, value) => sum + value, 0);
+};
+
+Array.prototype.product = function () {
+  return this.reduce((col, value) => col * value, 1);
+};
+
+Array.prototype.equals = function (arr) {
+  return (
+    this.length === arr.length && this.every((e, i) => Object.is(e, arr[i]))
+  );
+};
+
+const CHAR_WALL = '#';
+const CHAR_START = 'S';
+const CHAR_END = 'E';
+const DIR_EAST = 2;
+
+const dirs = {
+  orthogonal: [
+    [0, -1],
+    [-1, 0],
+    [0, 1],
+    [1, 0],
+  ],
+};
+
+function mod(a, b) {
+  return ((a % b) + b) % b;
+}
+
+const clockwise = (dir) => {
+  return mod(dir + 1, dirs.orthogonal.length);
+};
+
+const counterclockwise = (dir) => {
+  return mod(dir - 1, dirs.orthogonal.length);
+};
+
+function inRange(grid, row, col) {
+  return row >= 0 && row < grid.length && col >= 0 && col < grid[0].length;
+}
+
+function findTile(grid, char) {
+  const row = grid.findIndex((row) => row.includes(char));
+  const col = grid[row].findIndex((col) => col === char);
+
+  return [row, col];
+}
+
+const findMinScore = (grid, startRow, startCol, startDir, endRow, endCol) => {
+  const visited = new Set();
+  const distance = Array.from({ length: grid.length }, () =>
+    new Array(grid[0].length).fill(Infinity)
+  );
+  distance[startRow][startCol] = 0;
+
+  const q = [[0, startRow, startCol, startDir]];
+
+  while (q.length) {
+    q.sort(([acost], [bcost]) => bcost - acost);
+
+    const [cost, row, col, dir] = q.pop();
+    visited.add(`${row},${col}`);
+
+    if (row === endRow && col === endCol) {
+      break;
+    }
+
+    [
+      [0, dir],
+      [1000, clockwise(dir)],
+      [1000, counterclockwise(dir)],
+    ].forEach(([weight, dir]) => {
+      const [drow, dcol] = dirs.orthogonal[dir];
+      if (
+        inRange(grid, row + drow, col + dcol) &&
+        grid[row + drow][col + dcol] !== CHAR_WALL &&
+        !visited.has(`${row + drow},${col + dcol}`)
+      ) {
+        const nextCost = cost + weight + 1;
+
+        if (nextCost < distance[row + drow][col + dcol]) {
+          distance[row + drow][col + dcol] = nextCost;
+          q.push([nextCost, row + drow, col + dcol, dir]);
+        }
+      }
+    });
+  }
+
+  return distance;
+};
+
+const findMinScoreRoutes = (grid, startRow, startCol, endRow, endCol) => {
+  const routes = [];
+  const visited = new Map();
+
+  const q = [[[startRow, startCol], [[startRow, startCol]], 0, 0]];
+  while (q.length > 0) {
+    const [[row, col], history, currScore, currDir] = q.shift();
+
+    if (row === endRow && col === endCol) {
+      routes.push([history, currScore]);
+      continue;
+    }
+
+    const key = `${row},${col},${currDir}`;
+    if (visited.has(key) && visited.get(key) < currScore) {
+      continue;
+    }
+
+    visited.set(key, currScore);
+
+    dirs.orthogonal.forEach(([drow, dcol], dir) => {
+      const nextRow = row + drow;
+      const nextCol = col + dcol;
+
+      if (
+        grid[nextRow] &&
+        grid[nextRow][nextCol] !== CHAR_WALL &&
+        !history.some(([hrow, hcol]) => hrow === nextRow && hcol === nextCol)
+      ) {
+        if (dir === currDir) {
+          q.push([
+            [nextRow, nextCol],
+            [...history, [nextRow, nextCol]],
+            currScore + 1,
+            dir,
+          ]);
+        } else {
+          q.push([[row, col], history, currScore + 1000, dir]);
+        }
+      }
+    });
+  }
+
+  const minScore = Math.min(...routes.map(([_, score]) => score));
+  return routes.filter(([_, score]) => score === minScore);
+};
+
+function part1(data) {
+  const [startRow, startCol] = findTile(data, CHAR_START);
+  const [endRow, endCol] = findTile(data, CHAR_END);
+
+  return findMinScore(data, startRow, startCol, DIR_EAST, endRow, endCol)[
+    endRow
+  ][endCol];
+}
+
+function part2(data) {
+  const [startRow, startCol] = findTile(data, CHAR_START);
+  const [endRow, endCol] = findTile(data, CHAR_END);
+
+  const uniqueTiles = new Set(
+    findMinScoreRoutes(data, startRow, startCol, endRow, endCol)
+      .flatMap(([route]) => route)
+      .map(([row, col]) => `${row},${col}`)
+  );
+
+  return uniqueTiles.size;
+}
+
+module.exports = { parse, part1, part2 };