Leetcode No.168 Excel表列名称

class Solution {
public:
    string convertToTitle(int columnNumber) {
        string rs="";
        while(columnNumber>0){
            columnNumber--;
            int remainder=columnNumber%26;
            char ch='A'+remainder;
            rs='A'+ch+rs;

            int columnNumber=columnNumber/26;
            char ch2='A'+columnNumber;
            rs=ch2+rs;
            
        }
        return rs; 
    }
};

class Solution {
public:
    string convertToTitle(int columnNumber) {
        string rs="";
        while(columnNumber>0){
            int remain = columnNumber % 26 ? columnNumber % 26 : 26;
            //A的unicode编码是65
            char ch=64+remain;
            rs=ch+rs;
            columnNumber=(columnNumber-remain)/26;
        }
        return rs; 
    }
};