[Leetcode] Excel Sheet Column Title

The solution is also available here:https://gist.github.com/pyemma/93a32e641b90288867ae

/*
 * Author: Yang Pei
 * Problem: Excel Sheet Column Title
 * Source: https://oj.leetcode.com/problems/excel-sheet-column-title/
 * 
 * Note:
 * 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:
 * Recursive method or iterative method. 
 */
public class ExcelSheetColumnTitle {
 public String convertToTitle(int n) {
  if(n == 0)
   return "";
  return convertToTitle((n-1)/26) + (char)((n-1)%26 + 'A');
 }
 
 public String convertToTitle1(int n) {
  StringBuilder sb = new StringBuilder();
  while(n > 0) {
   sb.append((char)((n - 1) % 26 + 'A'));
   n = (n - 1) / 26;
  }
  sb = sb.reverse();
  return sb.toString();
 }
}