Day Ten, Part Two. Finally!
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Lewis Dale
parent
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commit
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4
index.ts
4
index.ts
@ -1,3 +1,3 @@
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import {runDayEleven} from "./src/day_eleven";
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import {runDayTen} from "./src/day_ten";
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runDayEleven();
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runDayTen();
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@ -1,4 +1,4 @@
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import {getFurthestDistance} from "./day_ten";
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import {getFurthestDistance, tilesContained} from "./day_ten";
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describe('Day Ten', () => {
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it.each([
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@ -21,4 +21,47 @@ LJ...`, 8]
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const result = getFurthestDistance(input);
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expect(result).toEqual(expected);
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});
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describe('Part Two', () => {
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it.each([
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['.....\n' +
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'.S-7.\n' +
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'.|.|.\n' +
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'.L-J.\n' +
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'.....', 1],
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['...........\n' +
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'.S-------7.\n' +
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'.|F-----7|.\n' +
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'.||.....||.\n' +
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'.||.....||.\n' +
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'.|L-7.F-J|.\n' +
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'.|..|.|..|.\n' +
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'.L--J.L--J.\n' +
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'...........\n', 4],
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['.F----7F7F7F7F-7....\n' +
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'.|F--7||||||||FJ....\n' +
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'.||.FJ||||||||L7....\n' +
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'FJL7L7LJLJ||LJ.L-7..\n' +
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'L--J.L7...LJS7F-7L7.\n' +
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'....F-J..F7FJ|L7L7L7\n' +
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'....L7.F7||L7|.L7L7|\n' +
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'.....|FJLJ|FJ|F7|.LJ\n' +
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'....FJL-7.||.||||...\n' +
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'....L---J.LJ.LJLJ...', 8],
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['FF7FSF7F7F7F7F7F---7\n' +
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'L|LJ||||||||||||F--J\n' +
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'FL-7LJLJ||||||LJL-77\n' +
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'F--JF--7||LJLJ7F7FJ-\n' +
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'L---JF-JLJ.||-FJLJJ7\n' +
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'|F|F-JF---7F7-L7L|7|\n' +
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'|FFJF7L7F-JF7|JL---7\n' +
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'7-L-JL7||F7|L7F-7F7|\n' +
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'L.L7LFJ|||||FJL7||LJ\n' +
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'L7JLJL-JLJLJL--JLJ.L', 10]
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])('should count the number of tiles fully contained within the loop', (input, expected) => {
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// const result = tilesContained(input);
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const result = tilesContained(input);
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expect(result).toEqual(expected);
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})
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});
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});
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@ -1,17 +1,24 @@
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import fs from "fs";
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import {window} from "./utils";
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type Grid = Tile[][];
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type Cell = [number, number];
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type Tile = 'S' | 'F' | 'J' | 'L' | '7' | '-' | '|' | '.';
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type Loop = string[];
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const isTile = (value: string): value is Tile => {
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return ['S', 'F', 'J', 'L', '7', '-', '|', '.'].includes(value);
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}
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const toString = (cell: Cell): string => {
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return cell.toString();
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return JSON.stringify(cell);
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}
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const fromString = (cell: string): Cell => {
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return JSON.parse(cell);
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}
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const getStart = (grid: Grid): Cell => {
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const row = grid.findIndex(row => row.includes('S'));
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const col = grid[row].findIndex(cell => cell === 'S');
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@ -28,12 +35,12 @@ const getSurrounding = (grid: Grid, [row, col]: Cell): Cell[] => {
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[row - 1, col + 1],
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[row + 1, col - 1],
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[row + 1, col + 1],
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] as Cell[]).filter((cell) => {
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const valid = isValid(grid, cell);
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const neighbour = neighbours(grid, cell).map(toString);
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return valid && neighbour.includes([row, col].toString());
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});
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] as Cell[]).filter((cell) => isInGrid(grid, cell));
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}
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const getConnectingNeighbours = (grid: Grid, [row, col]: Cell): Cell[] => {
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return getSurrounding(grid, [row, col]).filter((cell) =>
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isValid(grid, cell) && neighbours(grid, cell).map(toString).includes(toString([row, col]))
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);
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}
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const neighbours = (grid: Grid, [row, col]: Cell): Cell[] => {
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@ -74,35 +81,71 @@ const neighbours = (grid: Grid, [row, col]: Cell): Cell[] => {
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}
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}
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const isValid = (grid: Grid, [row, col]: Cell): boolean => {
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return row >= 0 && row < grid.length && col >= 0 && col < grid[row].length && grid[row][col] !== '.';
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function isInGrid(grid: Tile[][], [row, col]: Cell) {
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return row >= 0 && row < grid.length && col >= 0 && col < grid[row].length;
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}
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export const getFurthestDistance = (input: string): number => {
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const grid = input.split('\n').map(line => line.split('').filter(isTile));
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const isValid = (grid: Grid, cell: Cell): boolean => {
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return isInGrid(grid, cell) && grid[cell[0]][cell[1]] !== '.';
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}
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function parseGrid(input: string) {
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return input.split('\n').map(line => line.split('').filter(isTile));
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}
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function getMainLoop(grid: Grid): Loop {
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const start = getStart(grid);
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const queue = getSurrounding(grid, start);
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console.log(start, queue);
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const visited = new Set<string>([start.toString()]);
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const queue = [getConnectingNeighbours(grid, start)[0]];
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const visited = [toString(start)];
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while (queue.length > 0) {
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const current = queue.shift()!;
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const next = neighbours(grid, current);
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next.forEach(cell => {
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if (!visited.has(cell.toString()) && isValid(grid, cell)) {
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if (!visited.includes(toString(cell)) && isValid(grid, cell)) {
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queue.push(cell);
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visited.add(cell.toString());
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visited.push(toString(cell));
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}
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});
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}
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return visited;
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}
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return visited.size / 2;
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export const getFurthestDistance = (input: string): number => {
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const grid = parseGrid(input);
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const loop = getMainLoop(grid);
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return loop.length / 2;
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}
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export const area = (grid: Grid, loop: Loop): number => {
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// Use shoelace formula to calculate area of polygon
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const polygon = loop.map(fromString).filter((cell) => {
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const value = grid[cell[0]][cell[1]];
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return ['F', 'J', 'L', '7', 'S'].includes(value);
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});
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const total = window([...polygon, polygon[0]], 2).reduce((total, [a, b]) => {
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const [y1, x1] = a;
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const [y2, x2] = b;
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return total + (x1 * y2 - y1 * x2);
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}, 0);
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return Math.abs(total) / 2;
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}
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export const tilesContained = (input: string): number => {
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const grid = parseGrid(input);
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const loop = getMainLoop(grid);
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const loopArea = area(grid, loop);
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const boundaryPointsCount = loop.length;
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return loopArea - (boundaryPointsCount / 2) + 1;
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}
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export const runDayTen = () => {
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const input = fs.readFileSync('./inputs/day_ten_input.txt', 'utf8').trimEnd();
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const result = getFurthestDistance(input);
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const result = tilesContained(input);
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console.log(`Day Ten: ${result}`);
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}
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17
src/utils.ts
17
src/utils.ts
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export const matchAllAndThen = (input: string, pattern: RegExp, callback: (value: string, index: number) => void) => {
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[...input.matchAll(pattern)].map(match => {
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if (match && match.index !== undefined) {
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callback(match[0], match.index);
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}
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});
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[...input.matchAll(pattern)].map(match => {
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if (match && match.index !== undefined) {
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callback(match[0], match.index);
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}
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});
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}
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export const window = <T>(input: T[], size: number): T[][] => {
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return input.reduce((windows, value, index) => {
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if (index === input.length - size + 1) return windows;
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return [...windows, input.slice(index, index + size)];
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}, [] as T[][]);
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}
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