pascalTriangle.java

//Question: Given an integer 'numRows'. Generate Pascal's Triangle. (using 2d arraylist);
package twoDArray;
import java.util.*;

public class pascalTriangle {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        List<List<Integer>> ans = new ArrayList<>();

        System.out.print("Enter the number of rows: ");
        int numRows = sc.nextInt();

        for (int i = 0; i < numRows; i++) {
            List<Integer> l = new ArrayList<>();

            for (int j = 0; j <= i; j++) {
                // First and last element in each row is 1
                if (j == 0 || j == i) {
                    l.add(1);
                } else {
                    // Middle elements are sum of two elements above
                    l.add(ans.get(i - 1).get(j - 1) + ans.get(i - 1).get(j));
                }
            }

            ans.add(l);
        }

        // Print Pascal's Triangle
        for (List<Integer> ele : ans) {
            System.out.println(ele);
        }
    }
}