Excel Column Title

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 
solution:

Time: O(log(n))
Space: O(log(n))

public class Solution {
    public String convertToTitle(int A) {
        int size = 26;
        StringBuilder sb = new StringBuilder();
        int r = 0;
        while (A / 26 > 0) {
            r = A % 26;
            if (r == 0) { 
                r = 26;
                A -= 26;
            }
            sb.append((char) (r + 'A' - 1));
            A = A / 26;
        }
        r = A % 26;
        if (r != 0) { 
            sb.append((char) (r + 'A' - 1));
        }
        return sb.reverse().toString();
    }
}