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"
 

Constraints:

1 <= columnNumber <= 231 - 1

题目翻译：

给定一个整数columnNumber，返回它在Excel表中出现的相应列标题。

例如：

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


class Solution {
    // 定义方法，将整数转换为对应的Excel列标题
    public String convertToTitle(int columnNumber) {
        // 创建一个StringBuilder存储结果
        StringBuilder sb = new StringBuilder();
        // 当columnNumber大于0时，继续循环
        while (columnNumber > 0) {
            // 计算余数，注意需要先减一
            int remainder = (columnNumber - 1) % 26;
            // 将余数转换为字母，并加入结果字符串
            sb.append((char)('A' + remainder));
            // 计算商，注意需要先减一
            columnNumber = (columnNumber - 1) / 26;
        }
        // 返回结果字符串，需要先反转再转化为字符串
        return sb.reverse().toString();
    }
}