# 2457. Minimum Addition to Make Integer Beautiful
###### tags: `Leetcode` `Medium`
Link: https://leetcode.com/problems/minimum-addition-to-make-integer-beautiful/description/
## 思路 $O(logNlogN)$ $O(1)$
对于n=123456来说 如果现在n的digit sum大于target 下一个比n大并且digit sum小于等于target的就是123460 然后是123500
也就是```123456 -> 123460 -> 123500 -> 124000 -> 130000 -> 2000000```
所以如果n的digit sum大于target 我们就令```n = n//10+1```
## Code

class Solution {
    public long makeIntegerBeautiful(long n, int target) {
        long n0 = n, base = 1;
        while(sum(n)>target){
            n = n/10+1;
            base *= 10;
        }
        return n*base-n0;
    }
    private int sum(long n){
        int res = 0;
        while(n>0){
            res += n%10;
            n /= 10;
        }
        return res;
    }
}