(Leet Code c++)Excel Sheet Column Title

168. Excel Sheet Column Title

 

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 ...

 

Example 1:

Input: columnNumber = 1 Output: "A"

Example 2:

Input: columnNumber = 28 Output: "AB"

Example 3:

Input: columnNumber = 701 Output: "ZY"

Example 4:

Input: columnNumber = 2147483647 Output: "FXSHRXW"

 

Constraints:

• 1 <= columnNumber <= 231 - 1

 

class Solution {
public:
    string convertToTitle(int columnNumber) {
        string alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        string answer ="";
        
        while(columnNumber){
            int r = (columnNumber - 1) % 26;
            
            answer = alphabet[r] + answer;
            
            columnNumber = (columnNumber - 1) / 26;
        }
        
        return answer;  
    }
};