660. Remove 9（一种难理解的进制转换）

660. Remove 9

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

So now, you will have a new integer sequence: 1, 2, 3, 4, 5, 6, 7, 8, 10, 11, …

Given a positive integer n, you need to return the n-th integer after removing. Note that 1 will be the first integer.

example1:

Input: 9

Output: 10

Hint: n will not exceed 9 x 10^8.

nodes

因为删除的是最后一位9，所以实际上就是10进制转9进制的算法

int newInteger(int n) {
int ans = 0;
int base = 1;

while (n > 0){
ans += n % 9 * base;
n /= 9;
base *= 10;
}
return ans;
}