Question

link

Given a positive integer, return its corresponding column title as appear in an Excel sheet.

For example:

    1 -> A
    2 -> B
    3 -> C
    ...
    26 -> Z
    27 -> AA
    28 -> AB

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

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Analysis

This is pretty much a similar question. It’s pretty easy.

Code

public class Solution {
    public int titleToNumber(String s) {
        if (s == null || s.length() == 0) {
            return 0;
        }
        int sum = 0;
        for (char ch: s.toCharArray()) {
            sum *= 26;
            sum += (int) (ch - 'A' + 1);
        }
        return sum;
    }
}