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
class Solution {
public String convertToTitle(int n) {
StringBuilder result = new StringBuilder();
while(n>0){
n--;
result.insert(0, (char)('A' + n % 26));
n /= 26;
}
return result.toString();
}
}