2310. Sum of Numbers With Units Digit K

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.

class Solution {
public:
    int minimumNumbers(int num, int k) {
        if(num == 0) return 0;
        for(int i = 1; i <= 10; i++) {
            if(k * i <= num and k * i % 10 == num % 10)
                return i;
        }
        return -1;
    }
};