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
//26进制转化成10进制 Time: O(n), Space: (1) public int titleToNumber(String s) { if (s == null || s.length() == 0) { return 0; } int result = 0; for (int i = 0; i < s.length(); i++) { char c = s.charAt(i); result = result * 26 + c - 'A' + 1; } return result; }