728. Self Dividing Numbers

题目描述：

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.

解题思路：

一直思考有没有什么技巧，思考半天，没有头绪，最后使用暴力枚举。

代码：

class Solution {
public:
    vector<int> selfDividingNumbers(int left, int right) {
        vector<int> ret;
        for (int i = left; i <= right; ++i) {
            if (check(i))
                ret.push_back(i);
        }
        return ret;
    }
    bool check(int num) {
        int tmp = num;
        while (tmp != 0) {
            int div = tmp % 10;
            if (!div)
                return false;
            if (num % div != 0)
                return false;
            tmp /= 10;
        }
        return true;
    }
};