Description

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 
   ...

Example 1:

Input: 1
Output: "A"

Example 2:

Input: 28
Output: "AB"

Example 3:

Input: 701
Output: "ZY"

分析

题目的意思是：把十进制的数转换成excel的列标题

  • 这道题目比较简单的进制转换问题。重点看看代码二的奇妙解法。

代码一

class Solution {
public:
    string convertToTitle(int n) {
        string res;
        while(n){
            if(n%26==0){
                res.push_back('Z');
                n=n/26;
                n--;
                if(!n){
                    break;
                }
            }else{
               res.push_back(n%26+'A'-1); 
                n=n/26;
            }

        }
        
        reverse(res.begin(),res.end());
        return res;
    }
};

代码二

   std::string str( "" );
    while( n  )
    {
        str = char( ( n - 1 ) % 26 + 'A') + str;
        n = ( n  - 1 )/26;            
    }
    return str;
    
}

参考文献

​​168. Excel Sheet Column Title​​