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 

 其实就是10进制转26进制， 但是要注意的是A对应的是1，而不是0， 所以每次都要先-1。要倒过来输出。

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