adventOfCodeDay16.js

const [rulesRaw, yourTicketRaw, nearbyTicketsRaw] = input2.split('\n\n');
const yourTicket = yourTicketRaw
  .split('\n')[1]
  .split(',')
  .map((n) => Number(n));
const locations = new Array(yourTicket.length).fill(0).map((_, i) => i);
const rules = rulesRaw.split('\n').map((line) => {
  const [name, ruleStr] = line.split(': ');
  return {
    name,
    locations,
    ranges: ruleStr
      .split(' or ')
      .map((range) => range.split('-').map((n) => Number(n))),
  };
});

const nearbyTickets = nearbyTicketsRaw
  .split('\n')
  .slice(1)
  .map((ticket) => ticket.split(',').map((n) => Number(n)));

function ruleMatches(ranges, value) {
  return ranges.some((range) => {
    return range[0] <= value && value <= range[1];
  });
}

validTickets = nearbyTickets.filter((ticket) =>
  ticket.every((value) => rules.some((rule) => ruleMatches(rule.ranges, value)))
);
validTickets.unshift(yourTicket);

let index = 0;
while (!rules.every((rule) => rule.locations.length < 2)) {
  const ticket = validTickets[index];
  if (!ticket) {
    break;
  }
  rules.forEach((rule) => {
    rule.locations = rule.locations.filter((location) =>
      ruleMatches(rule.ranges, ticket[location])
    );
  });
  index++;
}

const foundRules = [];
while (rules.some((rule) => rule.locations.length === 1)) {
  const index = rules.findIndex((rule) => rule.locations.length === 1);
  const [foundRule] = rules.splice(index, 1);
  foundRules.push(foundRule);
  rules.forEach((rule) => {
    rule.locations = rule.locations.filter((l) => l != foundRule.locations[0]);
  });
}