2310. Sum of Numbers With Units Digit K
Medium
322
297

Given two integers `num` and `k`, consider a set of positive integers with the following properties:

• The units digit of each integer is `k`.
• The sum of the integers is `num`.

Return the minimum possible size of such a set, or `-1` if no such set exists.

Note:

• The set can contain multiple instances of the same integer, and the sum of an empty set is considered `0`.
• The units digit of a number is the rightmost digit of the number.

Example 1:

```Input: num = 58, k = 9
Output: 2
Explanation:
One valid set is [9,49], as the sum is 58 and each integer has a units digit of 9.
Another valid set is [19,39].
It can be shown that 2 is the minimum possible size of a valid set.
```

Example 2:

```Input: num = 37, k = 2
Output: -1
Explanation: It is not possible to obtain a sum of 37 using only integers that have a units digit of 2.
```

Example 3:

```Input: num = 0, k = 7
Output: 0
Explanation: The sum of an empty set is considered 0.
```

Constraints:

• `0 <= num <= 3000`
• `0 <= k <= 9`
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