LeetCode 5218. Sum of integers with K digits (enumeration)

1. subject

Here are two integers num and k , Consider a positive integer multiset with the following properties ：

• Every integer digit is k .
• The sum of all integers is num .

Returns the Minimum size , If there are no such multiple sets , return -1 .

Be careful ：
A multiset is similar to a set , But a multiset can contain more than one integer , The sum of empty multisets is 0 .
One digit number Is the rightmost digit of the number .

 Example  1：
 Input ：num = 58, k = 9
 Output ：2
 explain ：
 Multiple sets  [9,49]  Meet the conditions of the topic , And for  58  And the number of bits of each integer is  9 .
 Another conditional multiple set is  [19,39] .
 Can prove that  2  Is the minimum length of a multiple set that satisfies the problem condition .

 Example  2：
 Input ：num = 37, k = 2
 Output ：-1
 explain ： The number of digits is  2  The integers of cannot be added together to get  37 .

 Example  3：
 Input ：num = 0, k = 7
 Output ：0
 explain ： The sum of empty multisets is  0 .
 
 Tips ：
0 <= num <= 3000
0 <= k <= 9

source ： Power button （LeetCode）
link ：https://leetcode.cn/problems/sum-of-numbers-with-units-digit-k
Copyright belongs to the network . For commercial reprint, please contact the official authority , Non-commercial reprint please indicate the source .

2. Problem solving

• Special circumstances should be considered first , Then consider the number of single digits from 1 - 10 individual , Can we get num The number of digits , Be careful k* Number <= num

class Solution:
    def minimumNumbers(self, num: int, k: int) -> int:
        if num==0:
            return 0
        if k==0 and num%10==0: # num = 10, k = 0
            return 1
        for n in range(1, 11):
            if (k*n)%10 == num%10 and k*n <= num:
                return n
        return -1

36 ms 14.8 MB Python3

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