题目描述:

Related to question Excel Sheet Column Title

Given a column title as appear in an Excel sheet, return its corresponding column number.

For example:

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7
A -> 1
B -> 2
C -> 3
...
Z -> 26
AA -> 27
AB -> 28

二十六进制的转换.

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