77 lines
2.2 KiB
TypeScript
77 lines
2.2 KiB
TypeScript
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export type HeightMap = number[][];
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export async function readMap(path: string): Promise<HeightMap> {
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const text = await Deno.readTextFile(path);
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return text.split("\n").map((row) =>
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row.trim().split("").map((cell) => {
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const ret = parseInt(cell);
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if (isNaN(ret)) {
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return -5;
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}
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return ret;
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})
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);
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}
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export function displayMap(map: HeightMap) {
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console.log(map.map((row) => row.map(x=> x < 0 ? "." : x).join("")).join("\n"));
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}
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export type Pos = [number, number];
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export function getCell(map: HeightMap, [x, y]: Pos): number {
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return map[y][x];
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}
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export const TOP_HEIGHT = 9;
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export function countReachableTop(pos: Pos, map: HeightMap): number {
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const stack: {
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pos: Pos;
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height: number;
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}[] = [];
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const visited = new Set<string>();
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stack.push({ pos, height: getCell(map, pos) });
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let count = 0;
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while (stack.length > 0) {
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const { pos, height } = stack.pop()!;
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const [x, y] = pos;
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if (getCell(map, pos) === TOP_HEIGHT) {
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if (visited.has(pos.toString())) {
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continue;
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}
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visited.add(pos.toString());
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count++;
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continue;
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}
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for (const [dx, dy] of [[1, 0], [-1, 0], [0, 1], [0, -1]]) {
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const [nx, ny] = [x + dx, y + dy];
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if (nx < 0 || nx >= map[0].length || ny < 0 || ny >= map.length) {
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continue;
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}
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const nheight = getCell(map, [nx, ny]);
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if (nheight == height + 1) {
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stack.push({ pos: [nx, ny], height: nheight });
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}
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}
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}
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return count;
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}
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if (import.meta.main) {
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const map = await readMap("input.txt");
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displayMap(map);
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const data = map.map((row, y) => {
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return row.map((cell, x) => {
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if (cell === 0) {
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const count = countReachableTop([x, y], map);
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console.log("count reachable top from", [x, y]);
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return count;
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}
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return -5;
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});
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});
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displayMap(data);
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console.log(data.flat().reduce((a, b) => a + (b < 0 ? 0 : b ), 0));
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}
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