求所有满足条件的四位数: (1)这四位数是11的倍数; (2)a,b,c,d均是小于10 的互不相等的自然数; (3)b+c=a; (4)bc是完全平方数.

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashSet;

public class MM {
    public static void main(String args[]) {
        System.out.println(method());
        System.out.println(method().size());
    }

    public static ArrayList method() {
        ArrayList<Integer> list = new ArrayList<Integer>();
        for (int i = 1000; i < 10000; i++) {
        ArrayList<Integer> midList = new ArrayList<Integer>();
        HashSet<Integer> set = new HashSet<Integer>();
            if (i % 11 > 0) continue;
            //2
            char[] charArray = Integer.toString(i).toCharArray();
            for (char item : charArray) {
                int mid = (int) (item - '0');
                set.add(mid);
                midList.add(mid);
            }
            if (set.size() != charArray.length)continue;
            //3
           if(midList.get(0)!=midList.get(1)+midList.get(2))continue;
//            //4
                int bc=midList.get(1)*10+midList.get(2);
                int sqrtbc= (int)Math.sqrt(bc);
                if(sqrtbc*sqrtbc!=bc)continue;
            list.add(i);
        }
        return list;
    }
}