# Pascal triangle in java using array

Let’s learn pascal triangle in java using array.

## Pascal triangle in java using array

Here’s the algorithm on pascal triangle using arrays. First we have to use two dimensional array. First declare integer variables num, a, b, arr[][], p.

Let user input value of variable ‘num’. Now set p = num – 1. In the next step set two dimensional array arr = new int[num][num].

Now using two for loops repeat for a = 0 to num (a < num) and for b = 0 to a(b <= a). In the next step using if else check if b == 0 or b == 1 then set arr[a][b] = 1, else set arr[a][b] = arr[a – 1][b – 1] + arr[a – 1][b]; display output.

Now repeat for loop for a = 0 to num (a < num), for b = 0 to p and leave blank space. Decrease value of variable p by 1.

Repeat for loop for b = 0 to a (b <= a). print blank space. Here’s program on pascal triangle using array.

```import java.util.Scanner;
public class PascalTriangleUsingArray
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
int num, a, b, arr[][], p;
System.out.println("Please enter number of rows: ");
num = sc.nextInt();
p = num - 1;
arr = new int[num][num];
for(a = 0; a < num; a++)
{
for(b = 0; b <= a; b++)
if(b == 0 || b == a)
arr[a][b] = 1;
else
arr[a][b] = arr[a - 1][b - 1] + arr[a - 1][b];
}
System.out.println("Pascal's triangle: \n");
for(a = 0; a < num; a++)
{
for(b = 0; b <= p; b++)
System.out.print(" ");
p--;
for(b = 0; b <= a; b++)
System.out.print(arr[a][b] + " ");
System.out.println();
}
sc.close();
}
}
```

Output: