URAL 1014 Product Of Digits

• 注意特判 0 1
• 分解因子 从9到2

 1 import java.util.Scanner;
 2
 3 public class P1014
 4 {
 5     public static void main(String args[])
 6     {
 7         try (Scanner cin = new Scanner(System.in))
 8         {
 9             while (cin.hasNext())
10             {
11                 int n = cin.nextInt();
12                 StringBuilder builder = new StringBuilder();
13                 if (n == 0)
14                     System.out.println(10);
15                 else if (n == 1)
16                     System.out.println(1);
17                 else
18                 {
19                     for (int k = 9; k >= 2; k--)
20                         while (n % k == 0)
21                         {
22                             n /= k;
23                             builder.append(k);
24                         }
25                     if (n == 1)
26                         System.out.println(builder.reverse());
27                     else
28                         System.out.println(-1);
29                 }
30             }
31         }
32     }
33 }