[leetcode] 171. Excel Sheet Column Number 解题报告

题目链接：https://leetcode.com/problems/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 

思路：很简单的一个26进制转换成10进制，有一个陷阱是没有说明大小写是等价的。

代码如下：

class Solution {
public:
    int titleToNumber(string s) {
        int sum = 0;
        for(int i = 0; i< s.size(); i++)
            sum = sum*26 + toupper(s[i]) - 'A' + 1;
        return sum;
    }
};

python

class Solution(object):
    def titleToNumber(self, s):
        """
        :type s: str
        :rtype: int
        """
        ans = 0
        for index in range(len(s)):
            ans = ans*26 + ord(s[index]) - ord('A') + 1
        return ans;