Excel Sheet Column Title

题目描述：

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

这个题其实就是26进制换算~~~~
代码如下：

public class Solution {
public String convertToTitle(int n) {
StringBuilder sb=new StringBuilder();
while(n>0){
sb.insert(0,(char)((n-1)%26+'A'));
n=(n-1)/26;
}
return sb.toString();
}
}