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I have written a Sign function and am wondering whether it is correct or not (Stupid question to ask, I know!) I'm just interested in knowing whether this is the best method to solve this particular task:
template<typename T>
T sign(T n)
{
if(n < 0) return -1;
if(n > 0) return 1;
return 0;
}
Would this give accurate enough results for large datasets? Can anyone see a problem, that I haven't come across that may arise when putting this into a real-life context?
Thanks
I would change return 0; to return n;. If n is NaN, sign should return NaN, not 0.
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using concept of function overloading making a program to find maximum of 3 integer no.
I don't understand how do i show overload a function that is taking 3 integers only
You can use the fact that the maximum of three numbers is the bigger of 1 of the numbers and the maximum of the other two.
int maximum(int a,int b) { return /* ... */ }
int maximum(int a,int b, int c) { return /* ... */ }
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This problem is to output a single integer, the number of possible combinations calculated:
int power(int a, int n)
{
if (n == 0)
return 1;
// else
if (n % 2 == 0) {
int temp = power(a, n / 2);
return temp * temp;
}
// else
return a * power(a, n - 1);
}
This function uses a technique called exponentation by squaring.
It's a particularly efficient way of evaluating the power for integral type arguments. The standard C function uses floating point arguments, and the C standard doesn't require an exact result even if the floating point arguments represent whole numbers.
In C++ though you can probably rely on one of the overloads of std::pow that takes integral type arguments, and cast the result, subject to your making the necessary size checks. But again even the C++ standard does not require that the best possible result is returned (cf. std::sqrt under IEEE754), although one could reasonably regard a std::pow function that does not return the correct result for integral arguments to be defective.
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I'm writing a c++ implementation of RSA algorithm. It work but It takes hours to calcultate d key. Any help to make it work faster would be awesome.
unsigned __int64 calcolo_d(const unsigned __int64 eulero, const unsigned __int64 e) {
register unsigned __int64 d = 0;
while (!((e*d) % eulero == 1))
{
++d;
}
return d; }
What you are computing is the modular inverse of e mod eulero. This can be done efficiently via the extended euclidean algorithm.
There are many, many implementations out there to choose from.
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I have a little problem.
Who knows how we can calculate the log
base n with Shift_L or Shift_R?
for example: for n=2 we had this solution:
int log(int n){
int res = 0;
while((n>>=1))
res++;
return res;
}
You don't seem to want the logarithm for a base b, but the largest integer n so that n <= log_b(x). If that's the case, the following function should serve your needs:
int intlog(double base, double x) {
return (int)(log(x) / log(base));
}
well this is rather a math problem instead of an actuall programming problem, if i understand your problem correctly:
log_2 (x) = log_a (x) / log_a (2) where a can be any base.
Therefore you could use the math.h's function log(double)
double res = log(x)/log(2);
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#include <iostream>
using namespace std;
int main()
{
int a = 101;
return 0;
}
Question : How do I know that the number (1) is repeated twice in the variable
If you look at the code, you will see that the number 101 is assigned to the variable a and that number has the digit 1 twice in its decimal representation. So direct inspection is the way to go. I wouldn't even write the code for such a trivial requirement.
Use modulus 10 and division 10 to find it. Rough idea is,
while( a > 0 )
{
if( a % 10 == 1 )count_one++;
a=a/10;
}