代碼實現:
public class Main {
public static void main(String[] args) {
/* 方法一,思路:數的組成原理
* for (int i = 1; i < 10; i++) {
for (int j = 0; j < 10; j++) {
System.out.println(i * 1000 + j * 100 + j * 10 + i);
}
}*/
// 方法二 循環遍歷
int a = 0;
int b = 0;
int c = 0;
int d = 0;
for (int i = 1000; i < 10000; i++) {
a = i/1000;
b = i%1000/100;
c = i%100/10;
d = i%1000%100%10;
// System.out.println(a+" "+b+" "+c+" "+d);
if(a==d && c==b) {
System.out.println(i);
}
}
}
}