day-132.cpp

/*
  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


Constraints:

1 <= s.length <= 7
s consists only of uppercase English letters.
s is between "A" and "FXSHRXW".

*/

// Simple O(N) brute force solution
class Solution {
   public:
    int titleToNumber(string s) {
        int N = s.length();

        int multiplier = N - 1;
        int answer = 0;
        for (int idx = 0; idx < N; idx++) {
            int code = s[idx] & 31;
            int curr = pow(26, multiplier) * code;
            answer += curr;
            multiplier -= 1;
        }
        return answer;
    }
};