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58 lines
1.4 KiB
Java

/*
This is a Java Program to Implement Repeated Squaring Algorithm. Repeated squaring algorithm is used to compute xn efficiently.
*/
/**
** Java Program to Implement Repeated Squaring Algorithm
**/
import java.util.Scanner;
/** Class RepeatedSquaring **/
public class RepeatedSquaring
{
/** Function for repeated squaring **/
public double expBySquaring(double x, int n)
{
if (n < 0)
return expBySquaring(1 / x, -n);
else if (n == 0)
return 1;
else if (n == 1)
return x;
else if (n % 2 == 0)
return expBySquaring(x * x, n / 2);
else
return x * expBySquaring(x * x, (n - 1)/2);
}
/** Main function **/
public static void main (String[] args)
{
Scanner scan = new Scanner(System.in);
System.out.println("Repeated Squaring Algorithm Test\n");
/** Make an object of RepeatedSquaring class **/
RepeatedSquaring rs = new RepeatedSquaring();
/** Accept n , k **/
System.out.println("\nEnter n and k of (N ^ K)");
double n = scan.nextDouble();
int k = scan.nextInt();
double result = rs.expBySquaring(n, k);
System.out.println("\nResult : "+ result);
}
}
/*
Enter n and k of (N ^ K)
3 19
Result : 1.162261467E9
Repeated Squaring Algorithm Test
Enter n and k of (N ^ K)
7 -4
Result : 4.1649312786339016E-4