biginteger

问题 I want to create a bigInteger class that uses arrays in backend. BigInt a = 4321; // assume in BigInt class: array is {4,3,2,1} BigInt b = 2131; // assume in BignInt class: array is {2,1,3,1} BigInt sum = a + b; // array {6,4,5,1} I wrote this function to overload '+' operator to add the two numbers int* operator+(const uint32& other) const{ uint32 sum[n]; for(int i=0; i<n; i++){ sum[i] = (*this[i]) + other[i]; } return sum; } but it doesn't work. Note : assume the array size to be fixed. My

问题 I am trying to find the factorial of t numbers and input for each number n is provided by the user.The constraints are; 1 < t <= 100 1 < n <= 100 My code is : import java.util.Scanner; import java.math.BigInteger; public class fact { public static void main(String args[]) { int t = 0, i = 0; BigInteger result = BigInteger.valueOf(1); BigInteger x1 = BigInteger.ONE; Scanner sc = new Scanner(System.in); t = sc.nextInt(); BigInteger a[] = new BigInteger[t]; for(i = 0; i < t; i++) { a[i] =

问题 Since Rails 2.1, if you define a new column in a migration with the type set to :integer and the :limit set to 5 or more, the column actually created in your MySQL database will be of type BigInt. That's perfect. But I cannot figure out how to create a table with a BigInt primary key. Any clues? 回答1: I just stumbled upon this plugin: it seems to answer this very question. 回答2: This works in rails 3 not sure if it would work in rails 2. Throughout my app I needed my primary keys to be bigint

问题 What would be the best way to convert a 50-digit String to a BigInteger in Java? It doesn't have a valueOf(String) method, and I can't convert to Long because it's too small. 回答1: It does have a BigInteger(String) constructor :-) String S = "12345678901234567890123456789012345678901234567890"; BigInteger bi = new BigInteger(S); 回答2: How about... BigInteger bi = new BigInteger(my50DigitString); All those Xxx.valueOf() methods are alternatives to constructors because they allow for returning

问题 I tried to use BigInteger.Pow method to calculate something like 10^12345.987654321 but this method only accept integer number as exponent like this: BigInteger.Pow(BigInteger x, int y) so how can I use double number as exponent in above method? 回答1: There's no arbitrary precision large number support in C#, so this cannot be done directly. There are some alternatives (such as looking for a 3rd party library), or you can try something like the code below - if the base is small enough, like in

问题 We have an interesting challenge. We have to control access to data that reside in "bins". There will be, potentially, hundreds of thousands of "bins". Access to each bin is controlled individually but the restrictions can, and probably will, overlap. We are thinking of assigning each bin a position in a bitmask (1,2,3,4, etc..). Then when a user logs into the system, we look at his security attributes and determine which bins he's allowed to see. With that info we construct a bitmask for

问题 Assume the following Diffie-Hellman info which can also be found on this page 1)P string givenp = "00e655cc9e04f3bebae76ecca77143ef5c4451876615a9f8b4f712b8f3bdf47ee7f717c09bb5b2b66450831367d9dcf85f9f0528bcd5318fb1dab2f23ce77c48b6b7381eed13e80a14cca6b30b5e37ffe53db15e2d6b727a2efcee51893678d50e9a89166a359e574c4c3ca5e59fae79924fe6f186b36a2ebde9bf09fe4de50453"; BigInteger p = new BigInteger(HexToBytesv2(givenp)); 2)G BigInteger g = new BigInteger(2); 3)Merchant private key string

问题 I first wrote a code for Karatsuba algorithm using long. It works perfectly I think. Using the same logic I converted the code to BigInteger but for some reasons its giving StackOverflowError. I cant figure out why. Please help. EDIT1: The code for long also has a logical flaw. I am not sure what. EDIT2: The code for long works now. I switched a "%" operator with "/" by mistake. EDIT3: All good now. I changed .xor to .pow and == to .equals and fixed some bracket issues in the return statement

问题 There is a PMD rule saying one should avoid to instantiate BigInteger or BigDecimal if there is a predefined constant. BigInteger.ZERO // instead of new BigInteger(0) Would there be any other advantage than saving a few bytes? 回答1: it avoids the allocation of those few bytes and the need to collect them back later in a tight loop that can matter 回答2: Yes, saving a few JVM instructions. 回答3: Possibly performance, if you are instantiating a lot of 0s. An alternative for long/int argument is

问题 I need to invert a BigInteger . Let's say i have BigInteger x; and i need to calculate x.modPow(new BigInteger("-1"), p) . I receive the following error: java.lang.ArithmeticException: BigInteger not invertible . 回答1: Use BigInteger.modInverse() -- it will do what you want. If you read the docs for BigInteger.modInverse() (which performs the identical calculation, but more efficiently than your code; in fact presumably BigInteger.modPow() calls modInverse() for negative inputs before raising