Problem66.js

// Problem 66
//
// This problem was asked by Square.
//
// Assume you have access to a function toss_biased() which returns 0 or 1 with a probability that's not 50-50 (but also not 0-100 or 100-0). You do not know the bias of the coin.
//
// Write a function to simulate an unbiased coin toss.
//
// https://en.wikipedia.org/wiki/Fair_coin#Fair_results_from_a_biased_coin

/**
 * Returns 0 or 1 with a probability of 0.65-0.35
 * @returns {number}
 */
function tossBiased() {
  const rand = Math.random();
  return rand < 0.65 ? 0 : 1;
}

/**
 * Simulate Unbiased coin toss. Return 0 or 1
 * @returns {number}
 */
function simulateUnBiasedToss() {
  let toss1;
  let toss2;
  do {
    toss1 = tossBiased();
    toss2 = tossBiased();
  } while (toss1 !== toss2);
  return toss1;
}

export default simulateUnBiasedToss;