The main trick behind this algorithm is that if you, observing a stream of random integers, see an integer which binary representation starts with some known prefix, there is a higher chance that the cardinality of the stream is 2^(size of the prefix).
Hyperloglog 使用散列来实现随机性，但是如何证明散列一个值会产生随机输出呢？或者更严格地说，哈希是否保证像均匀输出一样的伪随机？
如果散列不能保证均匀输出，有没有办法可以对散列函数的非均匀性进行上限和量化？