【LeetCode】171. Excel Sheet Column Number 解题小结

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 

简单题，相当于26进制

class Solution {
public:
    int titleToNumber(string s) {
        int length = s.length();
        int res = 0;
        for(int i = 0; i < length; ++i){
            res = res * 26 +charToInt(s[i]);
        }
        return res;
    }
    
    int charToInt(char c){
        return (c - 'A' + 1);
    }
};