Draw Sierpinski Triangle using * in output.

Sierpinski.java

import java.util.Scanner;

public class Sierpinski {
    public static String[] T(int n) {
        if (n == 0) {
            String[] ans = new String[1];
            ans[0] = "*";
            return ans;
        }
        String[] prev = T(n - 1);
        int h = prev.length;
        int w = prev[0].length();
        String[] ans = new String[h * 2];
        for (int i = 0; i < h; i++) ans[i] = " ".repeat(w / 2 + 1) + prev[i] + " ".repeat(w / 2 + 1);
        for (int i = 0; i < h; i++) ans[i + h] = prev[i] + " " + prev[i];
        return ans;
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        String[] t = T(n);
        for (String s : t) System.out.println(s);
    }
}