← DSA Foundations
mediumBuild-up Logical Thinking (Patterns)

Pattern: Binary Number Triangle

Print a triangle of binary digits without spaces. Row i has i digits. The first row starts with 1; every step down or right flips the digit.

No external exercise

Work through the cases

3 examples

Input notation

An integer n from 1 through 30.

Expected result

The requested pattern, with one row per line.
Case 1

Input

3

Expected output

1
01
101
Case 2

Input

1

Expected output

1
Case 3

Input

2

Expected output

1
01

These notes use simplified input/output notation. The linked platform defines the method signature and judge format.

FROM IDEA TO IMPLEMENTATION

Understand the approach.

Compare the documented approaches below. Brute force, better, and optimal versions appear where available; a direct exercise may need only one approach.

The digit is 1 when row and column have the same parity, otherwise 0. Time: O(n²), row-buffer space: O(n).

import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        ArrayList<Long> values = new ArrayList<>();
        while (in.hasNextLong()) values.add(in.nextLong());
        long[] a = values.stream().mapToLong(Long::longValue).toArray();
        long n = a[0];
        for (int i = 0; i < n; i++) { for (int j = 0; j <= i; j++) System.out.print(1 - (i+j)%2); System.out.println(); }
    }
}

Reference code. Platform solutions may use supplied node types, imports, or collection libraries; foundational examples are complete programs.