JavaScript Celebrity Identification Problem

index.js

class Person {
  name;
  knownPersons = new Set();

  constructor(name) {
    this.name = name;
  }

  add(person) {
    this.knownPersons.add(person);
  }

  knows(person) {
    return this.knownPersons.has(person);
  }

  toString() {
    return this.name;
  }
}

const p1 = new Person('Michael Schumacher');
const p2 = new Person('Max Mustermann');
const p3 = new Person('Wolfgang Prety');
const p4 = new Person('Udo Jürgens');

p1.add(p2);
p1.add(p3);
p1.add(p4);
p3.add(p2);
p3.add(p1);
p4.add(p2);
p4.add(p3);

const findCelebrity = people => {
  const stack = [...people];

  // Elimination phsae
  while (stack.length > 1) {
    const a = stack.pop();
    const b = stack.pop();

    if (a.knows(b)) {
      stack.push(b);
    } else {
      stack.push(a);
    }
  }

  // Verification phase
  const candidate = stack[0];
  for (let i = 0; i < people.length; i++) {
    const person = people[i];
    if (
      candidate != person &&
      (candidate.knows(person) || !person.knows(candidate))
    ) {
      return null;
    }
  }

  return candidate;
};

const celebrity = findCelebrity([p1, p2, p3, p4]);
console.log(celebrity ? celebrity.toString() : 'No celebrity found');