168-excel-sheet-column-title

Question

https://leetcode.com/problems/excel-sheet-column-title/description/

Given a positive integer, return its corresponding column title as appear in an Excel sheet.

Example:

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

Thought Process

1. Mod
   1. we need to use mod to get the correct character
   2. Reverse the string at the end
   3. Time complexity O(log n)
   4. Space complexity O(1)

Solution

class Solution {
    public String convertToTitle(int n) {
        StringBuilder sb = new StringBuilder();
        while (n > 0){
            n--;
            sb.append((char)('A' + n % 26));
            n /= 26;
        }
        return sb.reverse().toString();
    }
}

Additional