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
/**
* @param {number} n
* @return {string}
*/
var convertToTitle = function(n) {
"use strict";
let result = [];
while (n) {
let ch = (n-1) % 26 + "A".charCodeAt();
result.push(String.fromCharCode(ch));
n = Math.floor((n-1)/26);
}
return result.reverse().join("");
};