Excel Sheet Column Title leetcode

Given a positive integer, return its corresponding column title as appear in an Excel sheet.

For example:

    1 -> A
    2 -> B
    3 -> C
    ...
    26 -> Z
    27 -> AA
    28 -> AB 

public class Solution {
    public String convertToTitle(int n) {
        StringBuilder res = new StringBuilder();
        while (n > 0) {
            n--;
            char tem = (char) (n % 26 + 'A');
            res.append(tem);
            n = n / 26;
        }
        return res.reverse().toString();
    }
}