Leetcode: Excel Sheet Column Number

Question:

Related to question Excel Sheet Column Title

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

Credits:
Special thanks to @ts for adding this problem and creating all test cases.

Thoughts:

这道题就是计算 二十六进制转十进制的问题，题目很简单，轻松搞定。

public class Solution {
    public int titleToNumber(String s) {
        int num = 0;
        for (int i = s.length() - 1; i >= 0; i--) {
            char c = s.charAt(i);
            int d = c - 'A' + 1;
            int j = s.length() - 1 - i;
            while (j > 0) {
                d *= 26;
                j--;
            }
            num += d;
        }
        
        return num;
    }
}