Column name from a given column number

class Solution{
    public:
    string colName (long long int n)
    {
        // your code here
        string help = "ABCDEFGHIJKLMNOPQRSTUVWXYZ",ans = "";
        while(n){
            int p = n % 26;
            if(p == 0){
                ans += help[25];
                n /= 26;
                n--;
            }
            else{
                ans += help[p-1];
                n /= 26;
            }
        }
        reverse(ans.begin(),ans.end());
        return ans;
    }

};