Excel Sheet Column Title (STRING - TYPE CONVERTION)

QUESTION

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 

FIRST TRY

class Solution {

public:

    string convertToTitle(int n) {

        int remain = n%26;

        n /= 26;

        string ret = "";

        char ch;

        while(1)

        {

            if(n == 0 && remain == 0)

            {

                return ret;

            }

            else if(n == 0)

            {

                ch = getChar(remain);

                return ch + ret;

            }

            ch = getChar(remain);

            ret = ch + ret; //char -> string, direct concat

            remain = n%26;

            n /= 26;

        }

        return ret;

    }

    

    char getChar(int n)

    {

        if(n != 0)

            return 'A'+ n - 1;

        else

            return 'Z';

    }

};

Result: Wrong

Input: 26
Output: "AZ"
Expected: "Z"

SECOND TRY

注意了余数为0的情况

class Solution {

public:

    string convertToTitle(int n) {

        int remain = n%26;

        n /= 26;

        string ret = "";

        char ch;

        while(1)

        {

            if(n == 0 && remain == 0)

            {

                return ret;

            }

            else if(n == 0)

            {

                ch = getChar(n,remain);

                return ch + ret;

            }

            ch = getChar(n,remain);

            ret = ch + ret; //char -> string, direct concat

            remain = n%26;

            n /= 26;

        }

        return ret;

    }

    

    char getChar(int& n, int remain)

    {

        if(remain != 0)

            return 'A'+ remain - 1;

        else

        {

            n -= 1;

            return 'Z';

        }

    }

};