Excel Sheet Column Number leetcode

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

思路简单，这里没有使用pow求n次方，而是使用变量t来保存

int titleToNumber(string s) {
int sum = s[s.length() - 1] - 'A' + 1;
int t = 26;
for (int i = s.length() - 2; i >= 0; --i, t *= 26)
sum += (s[i] - 'A' + 1) * t;
return sum;
}