PandigitalMultiples.java

package problem38;

/*
 Pandigital Multiples
 Problem 38
 Take the number 192 and multiply it by each of 1, 2, and 3:

 192 x 1 = 192
 192 x 2 = 384
 192 x 3 = 576
 By concatenating each product we get the 1 to 9 pandigital, 192384576. 
 We will call 192384576 the concatenated product of 192 and (1,2,3)

 The same can be achieved by starting with 9 and multiplying by 1, 2, 3, 4, and 5,
 giving the pandigital, 918273645, which is the concatenated product of 9 and 
 (1,2,3,4,5).

 What is the largest 1 to 9 pandigital 9-digit number that can be formed as the 
 concatenated product of an integer with (1,2, ... , n) where n > 1?
 */

public class PandigitalMultiples {

   public static void main(String[] args) {
      // numbers greater than 10000 have too many digits
      for (int i = 9876; i >= 0; i--) {
         String pandigital = "";
         int testNumber = 1;
         while (pandigital.length() < 9) {
            pandigital += i * testNumber;
            testNumber++;
         }
         if (pandigital.length() == 9) {
            boolean found = true;
            for (int j = 1; j <= 9; j++) {
               if (!pandigital.contains("" + j)) {
                  found = false;
                  j = 10; // exit for loop
               }
            }
            if (found) {
               System.out.println(pandigital);
               i = -1; // exit for loop
            }
         }
      }
   }
}