728. Self Dividing Numbers

A self-dividing number is a number that is divisible by every digit it contains.

For example, 128 is a self-dividing number because 128 % 1 == 0, 128 % 2 == 0, and 128 % 8 == 0.

Also, a self-dividing number is not allowed to contain the digit zero.

Given a lower and upper number bound, output a list of every possible self dividing number, including the bounds if possible.

Example 1:

Input:
left = 1, right = 22
Output: [1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 15, 22]

Note:

The boundaries of each input argument are 1 <= left <= right <= 10000.

class Solution {
public List<Integer> selfDividingNumbers(int left, int right) {
List<Integer> ans = new ArrayList<>();
for (int i = left; i <= right; ++i) {
if (valid(i)) {
ans.add(i);
}
}
return ans;
}

boolean valid (int num) {
int n = num;
while (num != 0) {
int c = num % 10;
if (c == 0) return false;
else {
if (n % c != 0) return false;
}
num /= 10;
}
return true;
}
}