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 注意：由于下标从1开始而不是从0开始，因此要减一操作。
static public string ConvertToTitle(int n) {string s = "";char c = ' ';while (n > 0) {int num = (n - 1) % 26;c = Convert.ToChar(num + 65);s = c + s;n = (n - 1) / 26;}return s;}