目前的想法是从右向左计算，可以考虑一下，能否从左向右计算。可以参考： Here is my java solution - LeetCode Discuss。
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
...
Example 1:
Input: "A" Output: 1
Example 2:
Input: "AB" Output: 28
Example 3:
Input: "ZY" Output: 701
link:{sourcedir}/_0171_ExcelSheetColumnNumber.java[role=include]