LeetCode Excel Sheet Column Number

1.题目

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 

2.解决方案

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

思路：26进制的概念。

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