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[LeetCode 171] Excel Sheet Column Number

Question

link

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.

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Math

Analysis

This question I’ve seen it quite a few time. It’s very standard integer conversion question.

Solution

Please read this post [ItInt5] Excel Decimal Conversion.

Code

recursively:

public class Solution {
    public String convertToTitle(int n) {
        if (n < 1) {
            return "";
        }
        n--;
        char ch = (char) ((n % 26) + 'A');
        return convertToTitle(n / 26) + ch;
    }
}