QuestionA.java

package Q17_09_Kth_Multiple;

import java.util.ArrayList;
import java.util.Collections;

public class QuestionA {

	public static ArrayList<Integer> allPossibleKFactors(int k) {
		ArrayList<Integer> values = new ArrayList<Integer>();
		for (int a = 0; a <= k; a++) { // 3
			int powA = (int) Math.pow(3,  a);
			for (int b = 0; b <= k; b++) { // 5
				int powB = (int) Math.pow(5,  b);
				for (int c = 0; c <= k; c++) { // 7
					int powC = (int) Math.pow(7, c);
					int value = powA * powB * powC;
					if (value < 0 || powA == Integer.MAX_VALUE || powB == Integer.MAX_VALUE || powC == Integer.MAX_VALUE) {
						value = Integer.MAX_VALUE;
					}
					values.add(value);
				}
			}
		}
		return values;
	}
	
	public static int getKthMagicNumber(int k) {
		ArrayList<Integer> possibilities = allPossibleKFactors(k);
		Collections.sort(possibilities);
		return possibilities.get(k);
	}
	
	public static void main(String[] args) {
		for (int i = 0; i < 50; i++) {
			System.out.println(i + " : " + getKthMagicNumber(i));
		}
	}
}