Excel Sheet Column Title & Excel Sheet Column Number

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，这题的数字不是从0开始，而是从1开始，我开始的时候用10进制的方式进行转换，发现不对。所以在程序里，用了n - 1.

 　　public String convertToTitle(int n) {
         StringBuilder sb = new StringBuilder();
         while (n > ) {
             int temp = (n - ) % ;
             sb.insert(, (char)(temp  + 'A'));
             n = (n - ) / ;
         }
         return sb.toString();
     }

Excel Sheet Column Number

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

For example:

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

 public class Solution {
     public int titleToNumber(String s) {
         // s = "AB";
         int total = ;
         for (int i = ; i < s.length(); i++) {
             total = total *  + s.charAt(i) - 'A' + ;
         }
         return total;
     }
 }