Leetcode171. Excel Sheet Column Number

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

Credits:

Special thanks to @ts for adding this problem and creating all test cases.

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C++代码
class Solution {
public:
int titleToNumber(string s) {
int n = s.size();
int i = n-1;
int sum = 0;
while (i>=0)
{
sum += (s[i] - 64)*pow((double)26, n-1-i);
i--;
}
return sum;

}
};