[LeetCode]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.

运用递归则可以不需逆置字符串

class Solution {
public:
    string convertToTitle(int n) {
        string tmp="";
        n--;
        tmp += (char)65 + n % 26;
        if(n<26) return tmp;
        else return convertToTitle(n/=26)+tmp;
    }
};