Armstrong_number.java

// Java program to determine whether the
// Number is Armstrong number or not
public class Armstrong {
	// Function to calculate x raised to the
	// power y
	int power(int x, long y)
	{
		if (y == 0)
			return 1;
		if (y % 2 == 0)
			return power(x, y / 2) * power(x, y / 2);
		return x * power(x, y / 2) * power(x, y / 2);
	}

	// Function to calculate order of the number 
	int order(int x)
	{
		int n = 0;
		while (x != 0) {
			n++;
			x = x / 10;
		}
		return n;
	}

	// Function to check whether the given number is
	// Armstrong number or not
	boolean isArmstrong(int x)
	{
		// Calling order function
		int n = order(x);
		int temp = x, sum = 0;
		while (temp != 0) {
			int r = temp % 10;
			sum = sum + power(r, n);
			temp = temp / 10;
		}

		// If satisfies Armstrong condition
		return (sum == x);
	}

	// Driver Program
	public static void main(String[] args)
	{
		Armstrong ob = new Armstrong();
		int x = 153;
		System.out.println(x + " : " + ob.isArmstrong(x));
		x = 1253;
		System.out.println(x + " : " + ob.isArmstrong(x));
	}
}