easyBuild-up Logical Thinking (Patterns)

Pattern: Right-Angled Triangle

Print n rows of stars. Row i contains i stars, starting from row 1.

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

Expected output

*
**
***

Case 2

Input

Expected output

Case 3

Input

Expected output

*
**

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.

Compute the leading spaces and star count for each row. Every printed character is necessary. Time: O(n²); the implementation buffers at most one row, O(n) space.

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 (long i = 0; i < n; i++) System.out.println(" ".repeat((int)(0)) + "*".repeat((int)(i+1)));
    }
}

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