LeetCode - Excel Sheet Column Title

https://leetcode.com/problems/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 

这道题就是进制转换问题，只是这里是26进制，而且每一位不是从0-25，而是从1-26

代码如下：

    public String convertToTitle(int n) {
        String rst = "";
        while(n>0){
            int val = (n-1)%26;
            rst = Character.toString((char)(val+'A')) + rst; 
            n = (n-1)/26;
        }
        return rst;
    }

注意这里用 （n-1）是因为十进制数中的1-26对应A-Z(0-25)