Excel Col to Number

题目：将excel的column变成数字。A -> 0, Z -> 25, AA -> 26

解题思路：

这道题就相当于将25进位转化成10进制。

代码：

public class ExcelColtoNumber {

    public int convert(String s){
        if(s == null || s.length() == 0){
            return 0;
        }
        char[] chars = s.toCharArray();
        int prev = 0;
        int curr = 0;
        for(int i = 0; i <= chars.length - 1; i++){
            char c = chars[i];
            curr = c - 'A' + 1;
            prev = prev * 26 + curr;
        }
        return prev - 1;
    }

    public static void main(String[] args){
        ExcelColtoNumber excelColtoNumber = new ExcelColtoNumber();
        int rst = excelColtoNumber.convert("BA");
        System.out.println(rst);
    }

}