solution.js

parkByState()

function parkByState(parks) {
  const result = parks.reduce((acc, park) => {
    let key = park.location.state;
    if (!acc[key]) {
      acc[key] = [];
    }
    acc[key].push(park)
    return acc
  }, {});
  return result;
}

function squareKmTotal(parks) {
  const parkSquareKms = parks.map((park) => park.areaInSquareKm);
  let total = parkSquareKms.reduce((acc, area) => acc + area);
  return total
}

/*Return an object where each key is the name of a park and 
each value is the state that park is in. */

function parkNameAndState(parks) {
  const result = parks.reduce((acc,park, ) => {
    acc[park.name] = park.location.state;
  return acc;
  }, {});
  return result
}