LeetCode - Easy - 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

thinking:

進制之間的裝換

solution:

public class ExcelSheetColumnNumber {
	public int titleToNumber(String s) {
		int result = 0;
		for (int i = 0; i < s.length(); i++) {
			result = result * 26 + (s.charAt(i) - 'A' + 1);
		}
		return result;
	}

	@//Test
	public void test() {
		Assert.assertEquals(1, titleToNumber("A"));
		Assert.assertEquals(2, titleToNumber("B"));
		Assert.assertEquals(3, titleToNumber("C"));
		Assert.assertEquals(26, titleToNumber("Z"));

		Assert.assertEquals(27, titleToNumber("AA"));
		Assert.assertEquals(28, titleToNumber("AB"));
		Assert.assertEquals(53, titleToNumber("BA"));

		System.out.println(titleToNumber("AAA"));
	}
}

reference

Excel Sheet Column Number