題目描述：

    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

    本題可以轉(zhuǎn)化為進(jìn)制轉(zhuǎn)換問(wèn)題，

LeetCode Excel Sheet Column Number

電腦資料

    思路：和2進(jìn)制轉(zhuǎn)10進(jìn)制有點(diǎn)類(lèi)似，對(duì)于AAA，可以理解為26進(jìn)制的轉(zhuǎn)換：1*26 + 1*26^2 + 1*26^3

    實(shí)現(xiàn)代碼：

public class Solution {    public int TitleToNumber(string s)     {    	var sum = 0;    	for(var i = s.Length - 1; i >= 0; i--){    		var d = s.Length - i;    		var n = Num(s[i]);    		sum += (int)Math.Pow(26, d-1) * n;    	}    	return sum;    }	private int Num(char c){	return (int)c - 64;}}