171. Excel Sheet Column Number (Easy)

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

Solution:

C:

int titleToNumber(char* s) {
    int len = strlen(s);
    int i, j = 1, result = 0;
    for(i = 0; i < len; i++, j *= 26) {
        result += (s[len - i - 1] - 'A' + 1) * j;
    }
    return result;
}