RestHouse

function main(allRooms, allPeople) {
    const BedsPerRoomType = {
        ['double-bedded']: 2,
        triple: 3,
    };

    prepareRooms(allRooms, BedsPerRoomType);

    let guestsInTeaHouse = fillTheRooms(allRooms, allPeople);

    allRooms.sort((a, b) => stringComparison(a, b, r => r.number));

    printResult(allRooms, guestsInTeaHouse);

    function printResult(allRooms, guestsInTeaHouse) {
        for (const room of allRooms) {
            console.log(`Room number: ${room.number}`);

            const allGuests = room.guests.sort((a, b) => stringComparison(a, b, g => g.name));
            for (const guest of allGuests) {
                console.log(`--Guest Name: ${guest.name}`);
                console.log(`--Guest Age: ${guest.age}`);
            }

            console.log(`Empty beds in the room: ${room.emptyBeds}`);
        }

        console.log(`Guests moved to the tea house: ${guestsInTeaHouse}`);
    }

    function stringComparison(a, b, getFactorFunc) {
        let result = 0;

        if (getFactorFunc(a) > getFactorFunc(b)) {
            result = 1;
        } else if (getFactorFunc(a) < getFactorFunc(b)) {
            result = -1;
        }

        return result;
    }

    function fillTheRooms(allRooms, allPeople) {
        let guestsInTeaHouse = 0;

        for (const {first, second} of allPeople) {
            let peopleForTeaHouse = 0;
            if (!peopleAreOfSameGender(first, second)) { // move in first free room
                peopleForTeaHouse = moveCoupleInFirstFreeDoubleRoom(allRooms, first, second);
            } else if (peopleAreOfSameGender(first, second)) { // move in a triple room
                peopleForTeaHouse = movePeopleInTripleRooms(allRooms, first, second);
            }

            guestsInTeaHouse += peopleForTeaHouse;
        }

        return guestsInTeaHouse;
    }

    function moveCoupleInFirstFreeDoubleRoom(allRooms, firstPerson, secondPerson) {
        const freeRoom = findFirstFreeRoomByType(allRooms, 'double-bedded');

        if (!freeRoom) {
            return 2;
        }

        freeRoom.guests.push(firstPerson, secondPerson);
        freeRoom.emptyBeds = 0;

        return 0;
    }

    function movePeopleInTripleRooms(allRooms, firstPerson, secondPerson) {
        let people = [firstPerson, secondPerson];

        const bonusRule = r => roomHasNoRuleGender(r) || r.ruleGender === firstPerson.gender;
        let freeRoom = findFirstFreeRoomByType(allRooms, 'triple', bonusRule);
        while (people.length &&
               freeRoom) {
            const guestToPlace = people[0];
            people = people.slice(1, people.length);

            freeRoom.guests.push(guestToPlace);
            freeRoom.emptyBeds--;

            if (roomHasNoRuleGender(freeRoom)) {
                freeRoom.ruleGender = guestToPlace.gender;
            }

            freeRoom = findFirstFreeRoomByType(allRooms, 'triple', bonusRule);
        }

        return people.length;
    }

    function peopleAreOfSameGender(firstPerson, secondPerson) {
        return firstPerson.gender === secondPerson.gender;
    }

    function prepareRooms(allRooms, BedsPerRoomType) {
        for (const room of allRooms) {
            const roomType = room.type;
            const bedsForRoom = BedsPerRoomType[roomType];

            room.emptyBeds = bedsForRoom;
            room.guests = [];

            if (roomType === 'triple') {
                room.ruleGender = '';
            }
        }
    }

    function findFirstFreeRoomByType(allRooms, type, bonusRule = () => true) {
       return allRooms.find(r => r.type === type && r.emptyBeds !== 0 && bonusRule(r));
    }

    function roomHasNoRuleGender(room) {
        return !room.ruleGender;
    }
}