Example: Pascal's Triangle using 2D Array in Java

// Pascal's Triangle using 2D Array
import java.util.Scanner;

// Main class containing the entry point of the program
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        // Step 1: Get the number of rows from the user
        System.out.print("Enter the number of rows for Pascal's Triangle: ");
        int numRows = scanner.nextInt();

        // Step 2: Declare and initialize the 2D array (jagged array)
        int[][] pascalTriangle = new int[numRows][];

        // Step 3: Populate the Pascal's Triangle
        for (int i = 0; i < numRows; i++) {
            // Each row 'i' has 'i + 1' elements
            pascalTriangle[i] = new int[i + 1];

            // The first and last elements of each row are always 1
            pascalTriangle[i][0] = 1;
            if (i > 0) {
                pascalTriangle[i][i] = 1;
            }

            // Calculate the inner elements of the current row
            // An element is the sum of the two elements directly above it
            for (int j = 1; j < i; j++) {
                pascalTriangle[i][j] = pascalTriangle[i-1][j-1] + pascalTriangle[i-1][j];
            }
        }

        // Step 4: Print the Pascal's Triangle
        System.out.println("\nPascal's Triangle with " + numRows + " rows:");
        for (int i = 0; i < numRows; i++) {
            // Add leading spaces for proper triangular alignment
            for (int k = 0; k < numRows - 1 - i; k++) {
                System.out.print("  "); // Adjust spacing as needed
            }
            for (int j = 0; j < pascalTriangle[i].length; j++) {
                System.out.printf("%4d", pascalTriangle[i][j]); // Print with formatting
            }
            System.out.println(); // Move to the next line for the next row
        }

        scanner.close();
    }
}