168. Excel Sheet Column Title（LeetCode）

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 
我想复杂了，下面是我的代码

class Solution {
public:
    string convertToTitle(int n) {
        map<int, string> m;
        vector<string> vet(1, "");
        string str = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        for (int i = 1; i <= 26; i++)
        {
            string s = "";
            s = str[i - 1];
            vet.push_back(s);

        }

        for (int i = 0; i <= 26; i++)
        {
            m.insert(pair<int, string>(i, vet[i]));
        }
            cout<<m[26]<<endl;
        stack<int> sta;
        string str1 = "";
        while (n)
        {
            if(n<=26)
            {
                sta.push(n);
                break;
            }
            if(n%26==0)
            {
                sta.push(26);
                n=n/26-1;
            }
            else
             {sta.push(n%26);
             n=n/26;
             }
        }
        while(sta.size())
        {
            str1+=m[sta.top()];
            sta.pop();
        }
        return str1;
    }
};

我看别人提交的代码：

class Solution {
public:
        string convertToTitle(int n) {
                string ret("");
                if (n <= 0)
                    return ret;

                while (n) {
                    --n;
                    ret += string(1, ((n) % 26) + 'A');
                    n /= 26;
                }
                reverse(ret.begin(), ret.end());
                return ret;
            }
        };