Problem 004

public class Problem4 {
    
    static int cal() {
        int max=0;
        int num=0;

        for (int i = 100; i < 1000; i++) {
            for (int j = 100; j < 1000; j++) {
                num=i*j;
                String s1=new StringBuilder(String.valueOf(num)).reverse().toString();
                if(s1.equals(num+"")) {
                    if(num>max) {
                        max=num;
                    }
                }
            }
        }
        return max;
    }

    public static void main(String[] args) {
        long start = System.currentTimeMillis();
        System.out.println(cal());
        long end = System.currentTimeMillis();
        System.out.println("runtime:" + (end - start));
    }

}