【leetcode】171. Excel Sheet Column Number

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

/**
 * @param {string} s
 * @return {number}
 */
var titleToNumber = function(s) {
    var n=s.length;
    var res=0;
    for(var i =0;i<n;i++){
        res=res*26+(s.charCodeAt(i)-"A".charCodeAt(0) +1);
    }
    return res;
};