Planidromic Number

Planidromic.java

/**
* Calculate how many palindromic n-digit numbers are present
* for 2 digit the palindromic numbers are 11, 22, 33, 44, 55, 66, 77, 88, 99 (total of 9)
**/
public static int numberOfPalindromicProblem(int n){
        if((n & 1) != 0){
            n = n/2;
        }else{
            n = n/2 -1;
        }
        return (int)(9 * Math.pow(10,n));
}

/**
* Calculate nth Palindromic number of k digit, e.g. 1st Palindromic number in 3 digit is 101
**/
 public static int printPalinDromeNumber(int n, int k){
        if(k<=0){
            throw new IllegalArgumentException("Invalid value of "+k);
        }

        int totalNumberOfPalinDromicNumber = numberOfPalindromicProblem(k);

        if(n<1 || n>totalNumberOfPalinDromicNumber){
            throw new IllegalArgumentException("Nth digit should be range between 1 and "+totalNumberOfPalinDromicNumber);
        }

        int temp = (k & 1) !=0 ? k/2 : k/2 -1;
        int palindrome = (int)Math.pow(10, temp);
        palindrome += n - 1;

        int actualNumber = palindrome;
        if ((k & 1)!=0)
            palindrome /= 10;

        while (palindrome!=0)
        {
            actualNumber = actualNumber*10 + palindrome % 10;
            palindrome /= 10;
        }

        return actualNumber;
    }