Let’s learn java program to display pascal triangle.

## Java program to display pascal triangle

Pascal triangle program in java is one of the common java interview question.

Pascal’s triangle is a triangle of binomial coefficients arranged in the form of a triangle.

Pascal’s triangle is named after french mathematician Blaise Pascal. Pascal’s triangle looks like this,

1 | ||||||||

1 | 1 | |||||||

1 | 2 | 1 | ||||||

1 | 3 | 3 | 1 | |||||

1 | 4 | 6 | 4 | 1 |

In the above pascal’s triangle there are five rows. First row starts with digit 1.

Then each digit in a row is the sum of left digit and right digit of above row.

Suppose, if a digit is missing in the above row, it is assumed as 0.

**NOTE:**

- diagonals adjacent to the border diagonals contain natural numbers in an order.
- sum of numbers in each row is twice the sum of numbers in above row.

Binomial coefficient can be calculated using formula,

C(n,r) = n!/((n-r)!*r!)

**Time complexity:** O(n²) where n is number of lines.

Here’s the java program to display pascal triangle.

import java.util.Scanner; public class PascalsTriangleJava { static int findFactorial(int number) { int factorial; for(factorial = 1; number > 1; number--) { factorial *= number; } return factorial; } // here's the function to display pascal's triangle static int printPascalTraingle(int num, int p) { returnfindFactorial(num) / (findFactorial(num - p) *findFactorial(p)); } public static void main(String[] args) { int row, a, b; System.out.println("Please enter number of rows: "); Scanner sc = new Scanner(System.in); row = sc.nextInt(); System.out.println("Here's is pascal's triangle: "); for(a = 0; a < row; a++) { for(b = 0; b < row - a; b++) { System.out.print(" "); } for(b = 0; b <= a; b++) { System.out.print(" " +printPascalTraingle(a, b)); } System.out.println(); } sc.close(); } }

**Output:**

Please enter number of rows: 6

Here’s is pascal’s triangle:

1

1 1

1 2 1

1 3 3 1

1 4 6 4 1

1 5 10 10 5 1

Please enter number of rows: 9

Here’s is pascal’s triangle:

1

1 1

1 2 1

1 3 3 1

1 4 6 4 1

1 5 10 10 5 1

1 6 15 20 15 6 1

1 7 21 35 35 21 7 1

1 8 28 56 70 56 28 8 1

Also read – TreeMap in java