题解 | HJ99#自守数#

import java.util.*;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        //按字符串处理
        int i = scanner.nextInt();
        int num = 0;
        for (int j = 0; j <= i; j++) {
            if (IsZishouNum(j)) {
                num++;
            }
        }
        System.out.println(num);
    }
    public static boolean IsZishouNum(int i) {
        String str = Integer.toString(i);
        int length = str.length();//位数
//        9376^2 = 87909376
//        int pow = (int)Math.pow(parseInt, 2);
        double sqrt = Math.pow(i, 2);
        String string = Integer.toString((int)sqrt);
        String substring = string.substring(string.length() - length);
        return substring.equals(str);
    }
}