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Solution Review: Pascal's Triangle

Understand how to create Pascal's Triangle by initializing arrays and using nested loops in Java. This lesson guides you through setting base cases and updating elements to form the triangle, strengthening your array manipulation and loop implementation skills.

We'll cover the following...

Solution

Java
class HelloWorld {

    public static void main( String args[] ) {

        int size = 5;

        int[][] pascalTr = new int[size][size];

        int row, col;

        //assign zero to every array element

        for (row = 0; row < size; row++)

            for (col = 0; col < size; col++) 

             pascalTr[row][col] = 0;

        //first and second rows are set to 1s

        pascalTr[0][0] = 1;

        pascalTr[1][0] = 1;

        pascalTr[1][1] = 1;



        for (row = 2; row < size; row++) {

            pascalTr[row][0] = 1;

            for (col = 1; col <= row; col++) {

                pascalTr[row][col] = pascalTr[row - 1][col - 1] + pascalTr[row - 1][col];

            }

        }



        //display the Pascal Triangle

        for (row = 0; row < size; row++) {

            for (col = 0; col <= row; col++) {

                System.out.print(pascalTr[row][col] + " ");

            }

            System.out.print("\n");

        }     

    }

}

Let’s assume that we have to print a triangle of size = 5 as follows:

1
1 1
1 2 1
1 3 3
...