Excel Sheet Column Number

Problem Statement - link #

Given a string columnTitle that represents the 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 ...

Examples #

Example 1:

Input: columnTitle = "A"
Output: 1

Example 2:

Input: columnTitle = "AB"
Output: 28

Example 3:

Input: columnTitle = "ZY"
Output: 701

Constraints #

• 1 <= columnTitle.length <= 7
• columnTitle consists only of uppercase English letters.
• columnTitle is in the range ["A", "FXSHRXW"]

Solutions #

class Solution {
public:
    int titleToNumber(string columnTitle) {
      int res = 0;
      for(auto c: columnTitle)
        res = res*26 + (c-'A') + 1; 
      return res;
    }
};