###### tags: `Leetcode` `easy` `string` `python` `c++`

# 168. Excel Sheet Column Title

## [題目來源:] https://leetcode.com/problems/excel-sheet-column-title/

## 題目:
Given an integer columnNumber, return its corresponding column title as it appears in an Excel sheet.

For example:

A -> 1
B -> 2
C -> 3
...
Z -> 26
AA -> 27
AB -> 28 

#### [圖片來源:] https://leetcode.com/problems/excel-sheet-column-title/

## 解題想法:
兄弟題目:參考 [171. Excel Sheet Column Number](/VYX6P02LTxScpXZD132rQA)

* 此題為數字轉字母
視為26進位，逐一求餘數，最終再將結果reverse

## Python:

class Solution(object):
    def convertToTitle(self, columnNumber):
        """
        :type columnNumber: int
        :rtype: str
        """
        dic="ABCDEFGHIJKLMNOPQRSTUVWXYZ"   
        res=[]
        while columnNumber:
            #-1: 若input = 1 則m=0 ->>>> dic[0]-> 得到A
            pos=(columnNumber-1)%26
            res.append(dic[pos])
            columnNumber=(columnNumber-1)//26
        res.reverse()
        return "".join(res)
        
if __name__ == '__main__':
    result = Solution()
    columnNumber = 28
    ans = result.convertToTitle(columnNumber)
    print(ans)

## C++:

#include<iostream>
#include<algorithm>
using namespace std;

class Solution{
public:
    string convertToTitle(int columnNumber){
        string dic="ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        string res;
        while (columnNumber>0){
            int pos = (columnNumber-1)%26;
            res+=dic[pos];
            columnNumber= (columnNumber-1)/26;
        }
        //<algorithm>
        reverse(res.begin(),res.end());
        return string(res);
    }
};

int main(){
    Solution res;
    int columnNumber = 701;
    cout<<res.convertToTitle(columnNumber)<<endl;
    return 0;
}