Question

For input you can either a console Scanner or a dialog box (a modal dialog) and the static method showInputDialog() of the JOptionPane class which is within the javax.swing package like this String name= newJOptionPane.showInputDialog(” Please enter your data:”). Then convert the String object to a number using Integer.parseInt() or Double.parseDouble()

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Write a Java program to calculate the first n ( the user enters the integer n) rows of the Pascal triangle. On demand display the first n rows of the Pascal triangle, a range of rows or an individual row n. Test by displaying the first 10 rows, the range 7:12 ( rows 7 through 12) or an individual row 15. The display of the first rows should looks like this:

                     1

                   1 1

                 1   2 1

               1 3   3 1

             1 4 6   4   1

and having the property that each row begins and ends with ones and every element is the sum of the two entries just above it.

Answer 1

Please refer the following JAVA code:

We have used console scanner for input and printed pascals triangle till n th row.

import java.io.*; 
import java.util.Scanner;

class Main { 

public static void printPascal(int n) 
{ 
    int val=n;
        for(int line = 1; line <= n; line++) 
        { 
            for(int k=0;k<val;k++){
                System.out.print(" ");
            }
            val--;      
            int C=1;
        
        for(int i = 1; i <= line; i++) 
        { 
                System.out.print(C+" "); 
                C = C * (line - i) / i; 
        } 
        System.out.println(); 
        } 
} 

public static void main (String[] args) { 
        int n;
        Scanner snr = new Scanner(System.in);
        System.out.println("Enter the number of rows till which you want to print pascals Triangle");
        n=snr.nextInt();
        printPascal(n); 
    } 
} 

Output for test case n=10 as metioned in question: