# 171. 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
# Solution
Approach 1: Scan the string and calculate.
# Code (Python)
Approach 1:
# Code (C++)
Approach 1:
class Solution {
public:
int titleToNumber(string s) {
int number = 0;
int level = 1;
for (int i = s.size() - 1; i >= 0; --i)
{
number += (s[i] - 'A' + 1) * level;
level *= 26;
}
return number;
}
};
class Solution {
public:
int titleToNumber(string s) {
int number = 0;
for (int i = 0; i < s.size(); ++i)
{
number = number * 26 + (s[i] - 'A' + 1);
}
return number;
}
};