// .....

const my_courses = [
    courses.find(c => c.subject == 198 && c.code == 205),
    courses.find(c => c.subject == 198 && c.code == 211),
    courses.find(c => c.subject == 590 && c.code == 101),
    courses.find(c => c.subject == 640 && c.code == 250),
];

function* cartesian(head, ...tail) {
    const remainder = tail.length > 0 ? cartesian(...tail) : [[]];
    for (let r of remainder)
        for (let h of head)
            yield [h, ...r];
}

function* permutations(a, b) {
    for (let i = 0; i < a.length; i++)
        for (let j = 0; j < b.length; j++)
            yield [a[i], b[j]];
}

function combinations(n, lst) {
    if (!n) return [[]];
    if (!lst.length) return [];

    var x = lst[0],
        xs = lst.slice(1);

    return combinations(n - 1, xs).map(function (t) {
        return [x].concat(t);
    }).concat(combinations(n, xs));
}

const times_compatible = (t0, t1) => !time.intersects(t0.interval, t1.interval) || t0.day != t1.day;
const sections_compatible = (s0, s1) => Array.from(cartesian(s0.times, s1.times)).reduceRight((acc, pair) => acc && times_compatible(...pair));
const schedule_compatible = sections => combinations(2, sections).reduceRight((acc, pair) => acc && sections_compatible(...pair));

const schedules = cartesian(...my_courses.map(c => c.sections));

let results = [];
for (let schedule of schedules) {
    if (schedule_compatible(schedule))
        results.push(schedule);
}
console.log(results);
console.log(`Valid: ${results.length} of ${my_courses.map(c => c.sections.length).reduceRight((acc, v) => acc * v)}`);