Example: Pascal's Triangle Iterative in Java

// Pascal's Triangle Iterative
import java.util.ArrayList;
import java.util.List;
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);
        System.out.print("Enter the number of rows for Pascal's Triangle: ");
        int numRows = scanner.nextInt();

        // Step 1: Use a list of lists to store the triangle
        List<List<Integer>> triangle = new ArrayList<>();

        // Step 2: Iterate through each row to build the triangle
        for (int i = 0; i < numRows; i++) {
            List<Integer> currentRow = new ArrayList<>();
            // Step 3: Add leading spaces for proper alignment (for printing only)
            for (int space = 0; space < numRows - 1 - i; space++) {
                System.out.print("  ");
            }

            // Step 4: Iterate through each element in the current row
            for (int j = 0; j <= i; j++) {
                if (j == 0 || j == i) {
                    currentRow.add(1); // The first and last elements of each row are 1
                } else {
                    // Current element is the sum of two elements from the previous row
                    int sum = triangle.get(i - 1).get(j - 1) + triangle.get(i - 1).get(j);
                    currentRow.add(sum);
                }
                System.out.printf("%4d", currentRow.get(j)); // Print the current element
            }
            triangle.add(currentRow); // Add the completed row to the triangle
            System.out.println(); // Move to the next line
        }
        scanner.close();
    }
}