168.excel-sheet-column-title.cpp

class Solution {
public:
    string convertToTitle(int columnNumber) {
        string ans = "";
        while(columnNumber > 0){
            ans += 'A' + (columnNumber-1)%26;
            columnNumber = (columnNumber-1)/26;
        }
        reverse(ans.begin(), ans.end());
        return ans;
    }
};