Easy to understand solution in Java. 
Complexity

Time complexity:
O(logn)


Space complexity:
O(logn)

Code
# Complexity
- Time complexity:
O(logn)

- Space complexity:
O(logn)

# Code
```java []
class Solution {
    public boolean isFascinating(int n) {
        StringBuilder sb = new StringBuilder();
        String concat = sb.append(n).append(2 * n).append(3 * n).toString();
        int m = concat.length();
        int[] freq = new int[m+1];
        for (char c : concat.toCharArray()) {
            int digit = Integer.parseInt(String.valueOf(c));
            freq[digit]++;
        }
        for (int i = 1; i <= 9; i++) {
            if (freq[i] != 1) {
                return false;
            }
        }

        if (freq[0] > 0) {
            return false;
        }

        return true;
    }
}
```
['Java']