1  /*
 2   * Write code to generate an expression that contanins all the 10 digits (0-9) and the 
 3   * sum of 2 3 digit no's should output a 4 digit no
 4   */
 5  
 6  public class assignment_23 {
 7    public static void main(String[] args) {
 8      for (int first = 102; first < 1000; first++) {
 9        for(int second = 103; second < 1000; second++) {
10          int third = first + second;
11          if(third >= 1000 && first < second) {   //If third is 4 digit no 
12            //To check for unique digits 
13            // We will use bit masking 
14            long combined_val = ((((first * 1000L) + second) * 10000) + third);    // 1000L typecasts int as long 
15            short ref = 0;
16  
17            while (combined_val != 0) {
18              int digit = (int)(combined_val % 10);
19              if ((ref & (1 << digit)) == 0) {
20                ref = (short)(ref | ( 1 << digit));   //Converting int to short 
21              }
22              else {
23                break;
24              }
25              combined_val /= 10;
26            }
27            if(combined_val == 0) {
28              System.out.println(first + " + " + second + " = " + third);
29            }
30          }
31        }
32      }
33    }
34  }