题解 | #自守数#

难度是如何确定自守数：采用String 的endWith

private static boolean isZiShouShu(int n) {

int re = n * n;

return Integer.toString(re).endsWith(Integer.toString(n));

}

import java.util.Scanner;

// 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 in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNextInt()) { // 注意 while 处理多个 case
            int a = in.nextInt();
            int c = 0;
            for (int i = 0; i <= a; i++) {
                if (isZiShouShu(i)) {
                    c++;
                }
            }
            System.out.println(c);
        }
    }

    private static boolean isZiShouShu(int n) {
        int re = n * n;
        return Integer.toString(re).endsWith(Integer.toString(n));
    }
}