price-calc.ts

interface Person {
    name: string;
    spent: number;
}

class Trip {
    private people: Person[];

    constructor() {
        this.people = [];
    }

    public addPerson(person: Person): void {
        this.people.push(person);
    }

    public get totalCost(): number {
        let total = 0;

        this.people.forEach(p => total += p.spent);

        return total;
    }

    public sortPeopleBySpent(): void {
        this.people.sort((a, b) => a.spent - b.spent);
    }

    public calculateCosts(): void {
        this.sortPeopleBySpent();

        let accumulator = 0;
        let averageCost = Math.ceil(this.totalCost / this.people.length);

        console.log(`Total spent: $${this.totalCost}, average per person: $${averageCost}`);

        this.people.reduce((personA, personB) => {
            let delta = averageCost - personA.spent;
            accumulator += delta;

            console.log(`${personA.name}:`);
            console.log(`  spent $${personA.spent}`);
            if (delta >= 0) {
                console.log(`  adds $${delta} to the pool`);
            } else {
                console.log(`  takes $${delta * -1} from the pool`);
            }
            console.log(`  sends $${accumulator} to ${personB.name}\n`);

            return personB;
        });
    }
}

let trip = new Trip();

trip.addPerson({ name: 'Warren', spent: 50 });
trip.addPerson({ name: 'Yannick', spent: 20 });
trip.addPerson({ name: 'Eric', spent: 220 });
trip.addPerson({ name: 'Jason', spent: 140 });
trip.addPerson({ name: 'Sam', spent: 150 });
trip.addPerson({ name: 'Avi', spent: 110 });
trip.addPerson({ name: 'Fonso', spent: 110 });
trip.addPerson({ name: 'Ryan', spent: 20 });
trip.addPerson({ name: 'Nebez', spent: 30 });

trip.calculateCosts();