Question

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

Difficulty:Easy

Category:Math

Analyze

Solution

class Solution {
 public:
  int titleToNumber(string s) {
    int ans = 0;
    for (const char c : s) {
      ans *= 26;
      ans += c - 'A' + 1;
    }
    return ans;
  }
};