[LeetCode][JavaScript]Excel Sheet Column Number

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

https://leetcode.com/problems/excel-sheet-column-number/

进制转换，比兄弟题简单。

/**
* @param {string} s
* @return {number}
*/
var titleToNumber = function(s) {
var map = [];
var codeA = "A".charCodeAt();

s = s.toUpperCase();
var power = 0;
var result = 0;
for(var i = s.length - 1; i >= 0; i--, power++){
var ch = s[i];
result += ( ch.charCodeAt() - codeA + 1 ) * Math.pow(26, power);
}

return result;
};