excel-sheet-column-number.js

/**
 * Source:  https://leetcode.com/problems/excel-sheet-column-number/
 * Tags:    [Math]
 * Level:   Easy
 * Updated: 2015-04-24
 * Title:   Excel Sheet Column Number
 * Auther:  @imcoddy
 * Content: 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
 *
 * Credits:Special thanks to @ts for adding this problem and creating all test cases.
 */

/**
 * @param {string} s
 * @return {number}
 */
var titleToNumber = function(s) {
    var str = '0ABCDEFGHIJKLMNOPQRSTUVWXYZ';
    var size = 26;
    var result = 0;
    for (var i=0; i < s.length; i++) {
        result = result * size + str.indexOf(s[i]);
        if (str.indexOf(s[i]) === 'Z') {
            result += size;
        }
    }
    console.log(result);
    return result;
};

titleToNumber('Y'); // 25
titleToNumber('Z'); // 26
titleToNumber('AA'); // 27
titleToNumber('YZ'); // 676
titleToNumber('ZZ');