题目：
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
解析：
实际上就是26进制，自己写的：
1 class Solution { 2 public: 3 int titleToNumber(string s) { 4 int n = 0; 5 for(int i = s.size()-1,j = 0; i >= 0; i--,j++) 6 n += (int(s[i])-64) * pow(26,j); 7 return n; 8 } 9 };
原文：http://www.cnblogs.com/raichen/p/4937331.html