Excel Sheet 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 

1. string convertToTitle(int n) {
2. if(n==0) {
3. return "";
4. }
5. string result="";
6. while(n!=0) {
7. int mod = n%26;
8. if(mod == 0) {
9. mod = 26;
10. }
11. char zifu = 'A' + mod - 1;
12. result = zifu + result ;
13. n = n/26;
14. if(mod == 26) n--;
15. }
16. return result;
17. }