Java: Create a 2-D array such that A[i][j] is false if I and j are prime, otherwise true

Last update on May 12 2025 13:12:14 (UTC/GMT +8 hours)

2D Prime Matrix

Write a Java program to create a two-dimensional array (m x m) A[][] such that A[i][j] is false if I and j are prime otherwise A[i][j] becomes true.

Visual Presentation:

Sample Solution:

Java Code:

import java.util.Scanner;

public class Solution {
    // Method to determine if two numbers are relatively prime
    public static int prime_cell(int a, int b) {
        // If either number is zero, return 1 as a special case
        if (a == 0 || b == 0) {
            return 1;
        }
        
        // If a is less than b, swap the values using a temporary variable
        if (a < b) {
            int t = a;
            a = b;
            b = t;
        }
        
        // Check if a is divisible by b
        if (a % b == 0) {
            return b; // Return b if it evenly divides a
        } else {
            return prime_cell(b, a % b); // Recursively call prime_cell method with b and the remainder of a/b
        }
    }

    public static void main(String[] args) {
        int n = 3; // Initialize variable 'n' with value 3
        boolean[][] A = new boolean[n][n]; // Create a 2D boolean array of size n x n
        
        // Loop through each element of the array
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                // Assign true if the result of prime_cell is 1 (relatively prime), otherwise assign false
                A[i][j] = prime_cell(i, j) == 1;
                System.out.print(A[i][j] + " "); // Print the value of the array element
            }
            System.out.println(); // Move to the next line after printing each row
        }
    }
} 

Sample Output:

true true true 
true true true 
true true false 

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Java program to create a 2D boolean array where an element is true if both its row and column indices are composite numbers.
• Write a Java program to build a 2D array that marks an element as true if either its row or column index is a prime number.
• Write a Java program to generate a 2D boolean matrix that uses a sieve method to determine if both indices are prime.
• Write a Java program to create a 2D array where each element is true if the sum of its indices is a prime number.

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