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