猜数字大小

function guessNumber(n: number): number {
  let left = 0, right = n
  while (left < right) {
    // use Math.floor instead of `>>`
    const mid = Math.floor(left + (right - left) / 2)
    if (guess(mid) <= 0) {
      right = mid
    } else {
      left = mid + 1
    }
  }

  return left
}