如何在java中找到像2 ^（10 ^ 9）这样的数的幂的幂 [英] How to find power of power of a number like 2^(10^9) in java

问题描述

Math.pow（）返回一个double值，只接受int作为参数... BigInteger没有查找BigInteger的函数^ BigInteger
通过循环执行它需要很长时间...
是还有我失踪的方式吗？

Math.pow() returns a double value and takes only int as parameters...BigInteger as no function for finding BigInteger^BigInteger Doing it through loops takes really long time... Is there any more way i am missing?

Thnx提前...

Thnx in advance...

推荐答案

您可以使用 BigInteger.pow（） 获取一个大指数。由于10 ⁹ 符合 int ，并且也可以完全表示为 double ，可以这样做：

You can use BigInteger.pow() to take a large exponent. Since 10⁹ fits into an int and is also exactly representable as a double, you can do this:

int exp = (int) Math.pow(10, 9);
BigInteger answer = BigInteger.valueOf(2).pow(exp);

对于大于 Integer.MAX_VALUE 。但是，您可以使用 BigInteger.modPow（BigInteger exponent，BigInteger m） 引发 BigInteger 到另一个 BigInteger 作为电源，模块第三个 BigInteger 。您只需要首先创建一个大于预期答案的 BigInteger 作为模数。

This obviously breaks down for exponents larger than Integer.MAX_VALUE. However, you can then use BigInteger.modPow(BigInteger exponent, BigInteger m) to raise a BigInteger to another BigInteger as a power, module a third BigInteger. You just need to first create a BigInteger that is larger than your expected answer to serve as a modulus.

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