leetcode 171: Excel Sheet Column Number

Given a column title as appear in an Excel sheet, return its corresponding column number.

For example:

A -> 1B -> 2C -> 3...Z -> 26AA -> 27AB -> 28 

解题思路

26进制转10进制
C = 3 = ‘C’-‘A’+1+26*0；
AA = 1+26=27=’A’-‘A’+1+26*1；
AB = 2+26=27 = ‘B’-‘A’+1+26*1；

代码实现

public class Solution {    public int titleToNumber(String s) {         s = s.toUpperCase();         char[] cs = s.toCharArray();         int result=0;         for(int i = 0 ; i < cs.length;i++){             result = result*26+(cs[i]-'A'+1);         }         return result;    }}