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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