softuni-students

function solve(arr) {
    const courses = new Map();
    // course regex
    const coursePattern = /(?<name>[\w#]+):\s(?<cap>\d+)/;
    const studentPattern = /(?<username>\w+)\[(?<credit>\d+)\] with email (?<email>\w+@\w+\.\w+) joins (?<course>[\w#]+)/;

    for (const e of arr) {
        if (coursePattern.test(e)) {
            const {name: course, cap: capacity} = e.match(coursePattern).groups;
            if (!courses.has(course)) {
                courses.set(course, {students: [], capacity: Number(capacity)});
            } else {
                courses.get(course).capacity += Number(capacity);
            }
        } else if (studentPattern.test(e)) {
            const {username, email,credit, course} = e.match(studentPattern).groups;

            if (courses.has(course)) {
                if (courses.get(course).capacity > 0) {
                    courses.get(course).students.push({username, email, credit: Number(credit)});
                    courses.get(course).capacity--;
                }
            }
        }
    }
    [...courses.entries()]
        .sort((a, b) => {
            return b[1].students.length - a[1].students.length;
        })
        .forEach(e => {
            console.log(`${e[0]}: ${courses.get(e[0]).capacity} places left`);
            courses.get(e[0]).students
                .sort((a, b) => {
                    return b.credit - a.credit;
                })
                .forEach(s => console.log(`--- ${s.credit}: ${s.username}, ${s.email}`));
        });
}