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]

解题要点：

从left到right，一个一个验证是否为有效的数。如果是，加入最终list。

class Solution {
    public List<Integer> selfDividingNumbers(int left, int right) {
        List<Integer> res = new ArrayList();
        while(left <= right){
            if(isValid(left)) res.add(left);
            left++;
        }
        return res;
    }
    
    public boolean isValid(int num){
        int n = num;
        while(num > 0){
            int temp = num % 10;
            if(temp == 0 || n % temp > 0) return false;
            num /= 10;
        }   
        return true;
    }
}