Leetcode/各大家 -- 168. Excel Sheet Column Title (Math)

168. Excel Sheet Column Title (Math)
easy
https://leetcode.com/problems/excel-sheet-column-title/

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 

 Microsoft Facebook Zenefits

思路： 只insert 值<=26时的单字母，所以用 n %26, 然后 n/=26。 下次依旧插在开头

public class Solution {
    public String convertToTitle(int n) {
        StringBuilder res = new StringBuilder();
        //appending digits <=26 (use n%26)
        while(n>0){
            n--;
            res.insert(0,(char)('A' + n%26));
            n /= 26; 
        }
        return res.toString();
    }
}