Allocate Money in Cents Without Rounding Drift

export function allocateCents(totalCents: number, weights: readonly number[]): number[] {
  if (!Number.isSafeInteger(totalCents)) throw new TypeError("totalCents must be a safe integer");
  if (!Array.isArray(weights) || weights.length === 0) {
    throw new TypeError("weights must be a non-empty array");
  }
  let weightSum = 0;
  for (const weight of weights) {
    if (!Number.isFinite(weight) || weight < 0) {
      throw new RangeError("weights must be non-negative numbers");
    }
    weightSum += weight;
  }
  if (weightSum === 0) throw new RangeError("at least one weight must be positive");
  if (!Number.isFinite(weightSum)) throw new RangeError("weight sum is too large");
  const sign = totalCents < 0 ? -1 : 1;
  const absolute = Math.abs(totalCents);
  const base = weights.map((weight) => Math.floor((absolute * weight) / weightSum));
  let remaining = absolute - base.reduce((sum, value) => sum + value, 0);
  const remainders = weights
    .map((weight, index) => ({ index, remainder: (absolute * weight) % weightSum }))
    .sort((left, right) => right.remainder - left.remainder || left.index - right.index);
  for (const entry of remainders) {
    if (remaining === 0) break;
    const current = base[entry.index];
    if (current === undefined) continue;
    base[entry.index] = current + 1;
    remaining -= 1;
  }
  return base.map((value) => value * sign);
}

console.log(allocateCents(1000, [1, 1, 1]));
console.log(allocateCents(100, [3, 7]));
console.log(allocateCents(5, [1, 1, 1]));
console.log(allocateCents(-100, [1, 1, 1]));