[LeetCode]--171. Excel Sheet Column Number

Related to question Excel Sheet Column Title

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 

Credits:
Special thanks to @ts for adding this problem and creating all test cases.

问题应该并不复杂，就跟String转int一样，只是这是个26进制的数而已。

public int titleToNumber(String s) {
        if (s.length() == 0 || s == null)
            return 0;
        int sum = 0;
        for (int i = 0; i < s.length(); i++) {
            sum = sum * 26 + (s.charAt(i) - 'A' + 1);
        }
        return sum;
    }

一次就Accept！