LeetCode 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.

思路分析：

遍历数组，对每个数字进行判断，符合条件则加入结果集

判断条件：循环判断，每次循环对该整数数字取余得到一位数，

终止条件：1.若取余得到的一位数为0则判断终止（0不可以作为被除数，即不符合条件），

               2.用取余得到的一位数对整数数字进行取余 结果不为0（说明不能被整除，不符合条件），跳出循环；

代码实现如下：

第一版：

class Solution {

    public List<Integer> selfDividingNumbers(int left, int right) {

        List<Integer> res = new ArrayList<>();

        for(int n = left; n <= right; n++){

           if(selfDividing(n)) res.add(n);

        }

        return res;

    }

    public boolean selfDividing(int n){

         int x = n ;

         while(x > 0){

            int d = x % 10;

            x = x / 10;

            if(d == 0 || (n % d != 0)) return false;

         }

        return true;

    }

}

第二版：

class Solution {

    public List<Integer> selfDividingNumbers(int left, int right) {

        List<Integer> ans = new ArrayList();

        for (int n = left; n <= right; ++n) {

            if (selfDividing(n)) ans.add(n);

        }

        return ans;

    }

    

    public boolean selfDividing(int n) {

        for (char c: String.valueOf(n).toCharArray()) {

            if (c == '0' || (n % (c - '0') != 0))

                return false;

        }

        return true;

    }

}