Java Program for Triangular Matchstick Number

Given a number X which represents the floor of a matchstick pyramid, write a program to print the total number of matchstick required to form a pyramid of matchsticks of x floors. Examples:

Input : X = 1
Output : 3

Input : X = 2
Output : 9

This is mainly an extension of triangular numbers. For a number X, the matchstick required will be three times of X-th triangular numbers, i.e., (3*X*(X+1))/2

Java

// Java program to find X-th triangular
// matchstick number
public class TriangularPyramidNumber {
    public static int numberOfSticks(int x)
    {
        return (3 * x * (x + 1)) / 2;
    }
    public static void main(String[] args)
    {
        System.out.println(numberOfSticks(7));
    }
}

Output

84

Time Complexity: O(1) as it is performing constant operations
Auxiliary Space: O(1)

Please refer complete article on Triangular Matchstick Number for more details!