Excel Sheet Column Number:有字母组成的26进制转换成10进制

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 

思路：26进制转换成10进制的按位运算，很简单，逐位累加求和即可。

class Solution {    public int titleToNumber(String s) {        if(s.length()==0) return 0;        int sum = 0;        int bit = 1;        for(int i = s.length()-1;i>=0;i--){            sum += ((int)(s.charAt(i)-'A')+1)*bit;            bit *=26;        }        return sum;    }}