88 lines
2 KiB
JavaScript
88 lines
2 KiB
JavaScript
import * as fs from "fs";
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class File {
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constructor(line) {
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this.length = line.length;
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this.data = line.map(v => ({value: v})); // index in data
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this.data[0].left = this.data[this.length-1];
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this.data[0].right = this.data[1];
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this.data[this.length-1].left = this.data[this.length-2];
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this.data[this.length-1].right = this.data[0];
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for (let i=1; i<this.length-1; ++i) {
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this.data[i].left = this.data[i-1];
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this.data[i].right = this.data[i+1];
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}
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this.data.forEach(v => { if (v.value === 0) this.head = v; });
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}
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get(i) {
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let it = this.head;
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for (let offset = i % this.length; offset > 0; --offset) {
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it = it.right;
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}
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return it.value;
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}
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mix() {
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this.data.forEach(v => {
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if (v.value !== 0) {
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let it = v;
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let offset; // javascript and modulo... what a nightmare!
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if (v.value > 0) offset = v.value % (this.length - 1);
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if (v.value < 0) offset = ((v.value * -1) % (this.length - 1)) * -1;
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if (offset !==0) {
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v.right.left = v.left;
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v.left.right = v.right;
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if (offset < 0) {
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for (; offset < 0; ++offset) {
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it = it.left;
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}
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v.right = it;
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v.left = it.left;
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v.left.right = v;
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v.right.left = v;
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} else {
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for (; offset > 0; --offset) {
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it = it.right;
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}
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v.right = it.right;
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v.left = it;
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v.left.right = v;
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v.right.left = v;
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}
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}
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}
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});
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}
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print() {
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let it = this.head;
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for (let offset = this.length; offset > 0; --offset) {
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console.log(it.value);
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it = it.right;
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}
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console.log("---");
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}
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}
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function load(filename) {
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return new File(
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fs.readFileSync(filename, "utf8")
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.trim()
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.split("\n")
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.map(line => parseInt(line))
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);
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}
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let example = load("example");
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let input = load("input");
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function solve(input) {
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input.mix();
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return input.get(1000) + input.get(2000) + input.get(3000);
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}
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const exampleOutput = solve(example);
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if (exampleOutput !== 3) {
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console.log("Example failed with " + exampleOutput);
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process.exit(1); // eslint-disable-line
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}
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console.log(solve(input));
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