#Leetcode# 171. Excel Sheet Column Number

https://leetcode.com/problems/excel-sheet-column-number/

 

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 
    ...

Example 1:

Input: "A"
Output: 1

Example 2:

Input: "AB"
Output: 28

Example 3:

Input: "ZY"
Output: 701

代码：

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

　　二十六进制转十进制