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| /**
* find vampire numbers from 1000 to 9999
*/
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
public class Programming {
public static void main(String[] args) throws IOException{
BufferedWriter bw = new BufferedWriter(new FileWriter("1.txt"));
for(int num = 1000;num <= 9999;num++){
boolean is = isVampireNumbers(num);
if(is) {
bw.write(num + " : " + is + "\r\n");
bw.flush();
}
}
}
/** the judgemental function
* need to be optimized
*/
public static boolean isVampireNumbers(int num){
String str = Integer.toString(num);
int count = str.length();
if(count % 2 == 0){
String[] strArr = str.split("");
boolean is = false;
int vnum1 = -1,vnum2 = -1;
for(int i = 0;i < strArr.length - 1;i++){
int n1 = Integer.parseInt(strArr[i]);
for(int j = i + 1;j < strArr.length;j++){
int n2 = Integer.parseInt(strArr[j]);
int[] m = new int[2];
int t = 0;
for(int k = 0;k < strArr.length;k++){
if(k != i && k != j) {
m[t] = k;
t++;
}
}
int m1 = Integer.parseInt(strArr[m[0]]);
int m2 = Integer.parseInt(strArr[m[1]]);
if((n1 == 0 && n2 == 0) || (m1 == 0 && m2 == 0))
continue;
vnum1 = (n1*10+n2);
vnum2 = (m1*10+m2);
int mul = vnum1 * vnum2;
if(mul == num){
is = true;
break;
}else{
vnum1 = (n1*10+n2);
vnum2 = (m2*10+m1);
mul = vnum1 * vnum2;
if(mul == num){
is = true;
break;
}else{
vnum1 = (n2*10+n1);
vnum2 = (m1*10+m2);
mul = vnum1 * vnum2;
if(mul == num){
is = true;
break;
}else{
vnum1 = (n2*10+n1);
vnum2 = (m2*10+m1);
mul = vnum1 * vnum2;
if(mul == num){
is =true;
break;
}
}
}
}
}
if(is){
System.out.println(vnum1 + "*" + vnum2);
return true;
}
}
}
return false;
}
}
|
