****Solution for java

since variable int is used,so on checking num variable,it should also be checked in integer type variable,so as on dividing we get some decimal value,i.e. ,an error.

****So,check if(num==val*val)

Here is Smart Number problem solution in Python Java C++ and C programming - https://programs.programmingoneonone.com/2021/07/hackerrank-smart-number-problem-solution.html

There is a bug in Java code, try using python, it passes all the test cases for the same changes made.

Perfect Squares have odd number of factors.

def is_smart_number(num):
    val = int(math.sqrt(num))
    if num  == val*val:
        return True
    return False

Java

public static boolean isSmartNumber(int num) {
        int val = (int) Math.sqrt(num);    
        if(num / val == val)
            return true;
        return false;
    }