Excel Sheet Column Number

【题目描述】

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 

【思路】

就是把 Excel Sheet Column Title的思路反过来。

【代码】

class Solution {public:    int titleToNumber(string s) {        int len=s.length();        int ans=0;        int cnt=1;        for(int i=len-1;i>=0;i--){            ans+=(s[i]-'A'+1)*cnt;            cnt=cnt*26;        }        return ans;    }};