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

Solution:

public class Solution {
  public int titleToNumber(String s) {
    int num = 0;
    for (int i = 0; i < s.length(); i++) {
      num = num * 26 + (int)(s.charAt(i) - 'A') + 1;
    }
    return num;
  }
}