View Code of Problem 3846

import java.math.BigInteger;

public class InterestingSet {

    public static void main(String[] args) {
        int n = 9;
        int k = 2;
        long rs = new InterestingSet().kthInterestingNumber(n, k);
        System.out.println(rs);
    }

    private long kthInterestingNumber(int n, int k) {
        char[] strNumber = Long.toBinaryString(n).toCharArray();
        for (int i = 0; i < k; i++) {
            strNumber = biggerThanIt(strNumber);
        }
        return parseBinaryLong(new String(strNumber));
    }

    private char[] biggerThanIt(char[] charNumbers) {
        int firstZero = charNumbers.length - 1;
        int firstOne = charNumbers.length - 1;
        for (int i = charNumbers.length - 1; i > 0; i--) {
            if (charNumbers[i] == '0') {
                firstOne = i;
            } else {
                firstZero = i;
            }

            if (firstZero > firstOne) {
                return swap(charNumbers, firstOne, firstZero);
            }
        }
        return charNumbers;
    }

    private char[] swap(char[] cs, int i, int j) {
        char x = cs[i];
        cs[i] = cs[j];
        cs[j] = x;
        return cs;
    }


    private static long parseBinaryLong(String s) {
        return new BigInteger(s, 2).longValue();
    }
}

/*
Main.java:3: error: class InterestingSet is public, should be declared in a file named InterestingSet.java
public class InterestingSet {
       ^
1 error
*/