leetCode刷题记录27_171_Excel Sheet Column Number

/*****************************************************问题描述*************************************************
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 
    ...
Example 1:
    Input: "A"
    Output: 1
Example 2:
    Input: "AB"
    Output: 28
Example 3:
    Input: "ZY"
    Output: 701
根据字符求数字，跟前面一题反过来了，简单多了
/*****************************************************我的解答*************************************************
/**
 * @param {string} s
 * @return {number}
 */
var titleToNumber = function(s) {
    var retNumber = 0;
    for(var index = 0; index < s.length; index++)
    {
        retNumber += (s.charCodeAt(index) - 64) * Math.pow(26,s.length - 1 - index); 
    }    
    return retNumber;
};
console.log(titleToNumber("ZY"));