168. Excel Sheet Column Title

 1 class Solution {
 2     public String convertToTitle(int n) {
 3         String res = new String();
 4         
 5         while( n != 0 ){
 6             int r = (n-1)%26;
 7             n = (n-1) / 26;
 8             res = ((char)(‘A‘ + r)) + res;
 9         }
10         
11         return res;
12     }
13 }