triangular_weighted_random.js

// Call this function with the number of levels in the queue.
// It will return the weighted random position.
function getPosition(n) {
  return n - tRoot(randomT(n));
}

function triangular(n) {
  return n * (n + 1) / 2;
}

function randomT(n) {
  return Math.floor(Math.random() * triangular(n));
}

function tRoot(n) {
  return Math.floor((Math.sqrt(8 * n + 1) - 1) / 2);
}