Excel表列序号

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

const titleToNumber = function(s) {
    let str = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    let res = 0

    for(let i = 0; i < s.length; i++)
        for(let j = 0; j < str.length; j++)
            if(s[i] === str[j])
                res +=  (j + 1) * 26**(s.length - 1 - i)
                
    return res;
};

const titleToNumber = function(s) {
    let res = 0

    for(let i = 0; i < s.length; i++)
        res +=  (s[i].charCodeAt()-65 +1) * 26**(s.length-1-i)

    return res;
};