Java学习-练习1

 1 package chapter3_Ex10;
 2 
 3 public class Vampire {
 4     
 5     public static void main(String[] args){
 6         int[] startDigit=new int[4];
 7         int[] productDigit=new int[4];
 8         for(int num1=10;num1<100;++num1){
 9             for(int num2=num1;num2<100;++num2){
10                 if((num1*num2)%9 != (num1+num2)%9)
11                     continue;
12                 int product=num1*num2;
13                 startDigit[0]=num1/10;
14                 startDigit[1]=num1%10;
15                 startDigit[2]=num2/10;
16                 startDigit[3]=num2%10;
17                 productDigit[0]=product/1000;
18                 productDigit[1]=product%1000/100;
19                 productDigit[2]=product%1000%100/10;
20                 productDigit[3]=product%1000%100%10;
21                 int count=0;
22                 for(int i=0;i<4;++i){
23                     for(int j=0;j<4;j++){
24                         if(startDigit[i]==productDigit[j]){
25                             ++count;
26                             startDigit[i]=-1;
27                             productDigit[j]=-2;
28                             
29                         }
30                     }
31                 }
32                 if(count==4){
33                     System.out.println(num1+" * "+num2+" = "+product);
34                 }    
35             }
36         }
37     }
38 }