81 lines
1.9 KiB
TypeScript
81 lines
1.9 KiB
TypeScript
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export async function readDiskData(path: string) {
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const text = await Deno.readTextFile(path);
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return text.trim().split("").map(Number);
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}
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export type Block = {
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id: number;
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} | null;
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export function translateToBlocks(data: number[]) {
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const blocks: Block[] = [];
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let idGen = 0;
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let empty = false;
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for (const num of data) {
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if (empty) {
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for (let i = 0; i < num; i++) {
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blocks.push(null);
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}
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} else {
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const id = idGen++;
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for (let i = 0; i < num; i++) {
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blocks.push({ id });
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}
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}
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empty = !empty;
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}
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return blocks;
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}
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export function compressBlocks(blocks: Block[]) {
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let left = 0;
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let right = blocks.length - 1;
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while (left < right) {
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// advance left if it's empty
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if (blocks[left] !== null) {
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left++;
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continue;
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}
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// advance right if it's not empty
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if (blocks[right] === null) {
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right--;
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continue;
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}
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// swap left and right
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blocks[left] = blocks[right];
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blocks[right] = null;
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left++;
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}
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return blocks;
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}
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export function displayBlocks(blocks: Block[]) {
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const strs = [];
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for (const block of blocks) {
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if (block === null) {
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strs.push(".");
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} else {
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strs.push(block.id);
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}
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}
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console.log(strs.join(""));
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}
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if (import.meta.main) {
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const data = await readDiskData("input.txt");
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const blocks = translateToBlocks(data);
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// displayBlocks(blocks);
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compressBlocks(blocks);
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// displayBlocks(blocks);
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// multiply index and sum
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const result = blocks.reduce((acc, block, i) => {
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if (block === null) {
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return acc;
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}
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return acc + block.id * i;
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}, 0);
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console.log(result);
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}
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