ExcelSheetColumnTitle.java

package math;

/**
 * Created by gouthamvidyapradhan on 12/08/2017.
 * Given a positive integer, return its corresponding column title as appear in an Excel sheet.
 * <p>
 * For example:
 * <p>
 * 1 -> A
 * 2 -> B
 * 3 -> C
 * ...
 * 26 -> Z
 * 27 -> AA
 * 28 -> AB
 */
public class ExcelSheetColumnTitle {

    private static final String CONST = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

    /**
     * Main method
     *
     * @param args
     * @throws Exception
     */
    public static void main(String[] args) throws Exception {
        System.out.println(new ExcelSheetColumnTitle().convertToTitle(52));
    }


    public String convertToTitle(int n) {
        StringBuilder ans = new StringBuilder();
        while (n > 0) {
            int mod = n % 26;
            n /= 26;
            if (mod == 0) {
                ans.append('Z');
                n -= 1;
            } else {
                ans.append(CONST.charAt(mod - 1));
            }
        }
        return ans.reverse().toString();
    }

}