168. 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

Credits:

Special thanks to @ifanchu for adding this problem and creating all test cases.

public class Solution {
public String convertToTitle(int n) {
String ret = "";
while(n>0){
int a = n%26;
n = n/26;
if(a==0){ret='Z'+ret;n=n-1;}else{
ret=(char)('A'-1+a)+ret;
}
}
return ret;
}
}