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

这个可以看成是一个26进制的问题, 但是没有0, 发现没有

所以, 取余的时候要单独处理了

class Solution {
public:
    char str[27]="ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    string convertToTitle(int n)
    {
        string result="";
        while(n)
        {
            if(n%26)
            {
                result.push_back(str[(n%26)-1]);  
                n /= 26;
            }
            else
            {
                result.push_back(str[25]);
                n = (n-26)/26;
            }
        }
    reverse(result.begin(),result.end());
    return result;
    }
};

Excel Sheet Column Title