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Excel Sheet Column Number - Math - Easy - LeetCode - MiniTV

Excel Sheet Column Number - Math - Easy - LeetCode - मिनी टीवी

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".

public class Solution {
    public int TitleToNumber(string s) {
        int res = 0;
        for(int i=s.Length-1, j=0;i>=0;i--,j++){
            res += (int)Math.Pow(26,j)*(s[i]-64);            
        }
        return res;
    }
}

Time Complexity: O(n)

Space Complexity: O(1)