LeetCode-Excel表列名称-简单

给你一个整数 columnNumber ，返回它在 Excel 表中相对应的列名称。

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

输入：columnNumber = 1
输出："A"

输入：columnNumber = 28
输出："AB"

输入：columnNumber = 701
输出："ZY"

输入：columnNumber = 2147483647
输出："FXSHRXW"

• 1 <= columnNumber <= 231 - 1

		public String converToTitle(int columnNumber) {
        StringBuilder result = new StringBuilder();
        while (columnNumber != 0) {
            int x = columnNumber % 26 - 1;
            columnNumber /= 26;
            if (x < 0 ) {
                x = 25;
                columnNumber --;
            }
            char sum = (char) (65 + x);
            result.append(sum);
        }
        return result.reverse().toString();
    }