leetcode讲解--728. Self Dividing Numbers

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.

这道题需要注意几点：

1. 不要直接对i进行操作，而是复制一份，对复制品进行操作
2. 对0的过滤，0不能做除数
3. while的控制条件应该是num!=0，而非num/10!=0，否则会过滤掉个位数

Java代码

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