2310. 个位数字为 K 的整数之和

参考：

https://leetcode.cn/problems/sum-of-numbers-with-units-digit-k/solution/ge-wei-shu-zi-wei-k-de-zheng-shu-zhi-he-c8nlx/

class Solution {
public:
    int minimumNumbers(int num, int k) {
      // 空多重集的和为 0 
      if(num == 0){
        return 0;
      }    
      
      // 参考官方题解
      for(int i = 1; i <= 10; i++){
        if(i * k <= num && (num - (i * k)) % 10 == 0){
          return i;
        }
      }
      
      return -1;
    }
};