Excel Sheet Column Number
https://leetcode.com/problems/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
Implementation :
class Solution {
public int titleToNumber(String s) {
if(s == null || s.length() == 0)
return 0;
int column = 0;
int unit = 0;
for(int i = s.length()-1; i >= 0; i--) {
char ch = s.charAt(i);
int value = (ch - 'A') + 1;
int pos = (int) Math.pow(26, unit);
column = column + (pos * value);
unit++;
}
return column;
}
}