87 lines
3.0 KiB
TypeScript
87 lines
3.0 KiB
TypeScript
import { readFormat } from "./solve_1.ts";
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async function main() {
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const path = new URL("input.txt", import.meta.url).pathname;
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const { order, pageNumbers } = await readFormat(path);
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// create order map
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const orderMap = new Map<number, Set<number>>();
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for (const { left, right } of order) {
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const leftSet = orderMap.get(left) ?? new Set<number>();
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leftSet.add(right);
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orderMap.set(left, leftSet);
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}
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const completedSetMap = orderMap;
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// check order is valid or not by comparing with pageNumbers
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function checkPageNumberOrder(pageNumbers: number[]): boolean {
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const notAllowed = new Set<number>();
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for (let i = pageNumbers.length - 1; i >= 0; i--) {
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const current = pageNumbers[i];
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if (notAllowed.has(current)) {
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// console.log("not allowed", current, notAllowed );
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return false;
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}
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notAllowed.add(current);
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const biggerThanCurrent = completedSetMap.get(current);
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biggerThanCurrent?.forEach((elem) => notAllowed.add(elem));
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}
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return true;
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}
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function findErrorIndex(n: number, pages: number[]) {
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return pages.findIndex(page => {
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const biggerThanCurrent = completedSetMap.get(page);
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if (biggerThanCurrent) {
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return biggerThanCurrent.has(n);
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}
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return false;
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})
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}
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function correctPageNumberOrder(pageNumbers: number[]): number[] {
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const result = [...pageNumbers];
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const notAllowed = new Set<number>();
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for (let i = result.length - 1; i >= 0; i--) {
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const current = result[i];
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if (notAllowed.has(current)) {
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const p = result.slice(i + 1);
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const errorIndex = findErrorIndex(current, p);
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if (errorIndex === undefined) {
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// could not happen
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throw new Error("cannot correct the order");
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}
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const ei = errorIndex + i + 1;
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result[i] = result[ei];
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result[ei] = current;
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return correctPageNumberOrder(result);
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}
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notAllowed.add(current);
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const biggerThanCurrent = completedSetMap.get(current);
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biggerThanCurrent?.forEach((elem) => notAllowed.add(elem));
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}
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return result;
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}
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let sum = 0;
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for (const pages of pageNumbers) {
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if (!checkPageNumberOrder(pages)) {
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// correct the order
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const corrected = correctPageNumberOrder(pages);
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if (!checkPageNumberOrder(corrected)) {
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console.log("cannot correct the order", pages);
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console.log("corrected", corrected);
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throw new Error("cannot correct the order");
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}
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const middle = corrected[corrected.length >> 1];
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sum += middle;
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}
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}
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console.log(sum);
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}
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if (import.meta.main) {
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main();
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}
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