660. Remove 9

Start from integer 1, remove any integer that contains 9 such as 9, 19, 29…

Now, you will have a new integer sequence [1, 2, 3, 4, 5, 6, 7, 8, 10, 11, …].

Given an integer n, return the nth (1-indexed) integer in the new sequence.

class Solution {
    int conversion(int n) {
        long res = 0, i = 1;
        while(n) {
            res = res + (n%9) * i;
            n/=9;
            i *= 10;
        }
        return res;
    }
public:
    int newInteger(int n) {
        return conversion(n);
    }
};