Finding modulo of large numbers squared

问题

I am currently writing a program that requires the calculation of:

(x^2) mod y

Both these numbers are integers. Both can be large numbers, though they never exceed 10^9.

That is still enough to overflow integer for x squared. Speed is crucial for this code so gradual multiplication is not usable.

Thank you.

回答1:

You can take a reference from this post

This should be a relatively easy example. 4^23=2^46. Now, since 2^5=32≡1(mod31),

2^46=(2^5)9×2=32^9×2≡1×2≡2(mod31)

回答2:

The solution was really simple. I used Long, instead of int and it works.

来源：https://stackoverflow.com/questions/22493409/finding-modulo-of-large-numbers-squared