[171]Excel表列序号

class Solution {
    public int titleToNumber(String s) {
        int n = 0;
        for (int i = 0; i < s.length(); i++) {
            n= n * 26 + (int)s.charAt(i) - 64;
        }
        return n;
    }
}

```
class Solution:
    def titleToNumber(self, s: str) -> int:
        num = 0
        for i in s:
            num = num * 26 + (ord(i) - 64)
        return num