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# 171.Excel Sheet Column Number

**171.Excel Sheet Column Number**

难度:Easy

> 给定一个Excel表格中的列名称，返回其相应的列序号。

```
例如，

    A -> 1
    B -> 2
    C -> 3
    ...
    Z -> 26
    AA -> 27
    AB -> 28 
    ...
示例 1:
输入: "A"
输出: 1

示例 2:
输入: "AB"
输出: 28

示例 3:
输入: "ZY"
输出: 701
```

代码如下：

```
class Solution {
public:
    int titleToNumber(string s) {
        int res=0;
        for(int c:s)
            res=c-'A'+1+res*26;
        return res;
    }
};
```