Brilliant Numbers in JavaIn this section, we will learn what is brilliant number and also create Java programs to check if the given number is a brilliant number or not. The brilliant number program is frequently asked in Java coding interviews and academics. Brilliant NumberA number is called a brilliant number if the product of two prime numbers (say p and q) such that a total number of digits present in the prime number p must be equal to the total number of digits present in the prime number q. Since a brilliant number is a product of two prime numbers, therefore, each brilliant number is also a semiprime number. However, viceversa is not true. Mathematically, N is said to be a brilliant number iff N = p * q and Number of digits in p = Number of digits in q. Let's understand it through examples. Example 1: Input: 15 Output: 15 is a brilliant number. Explanation: 15 is the product of two prime numbers 3 and 5. Also, the number of digits in the number 3, which is 1, is equal to the number of digits in the number 5. Hence, 15 is a brilliant number. Example 2: Input: 50 Output: 50 is a not brilliant number. Explanation: 50 is the product of two numbers 5 and 10. However, 10 is not a prime number. Hence, 50 is not a brilliant number. Example 3: Input: 22 Output: 2 is a not brilliant number. Explanation: 22 is the product of two prime numbers 2 and 11. Also, the number of digits in the number 2, which is 1, is not equal to the number of digits in the number 11, which is 2. Hence, 2 is not a brilliant number. Validation For the Brilliant NumberTo check whether n is a brilliant number or not, we need to check whether the number is semiprime or not.
Observe the following algorithm. Step 1: Take the number n. Step 2: Compute the total number of factors for the number n. Step 3: Check whether the total count of factors computed in step 2 is equal to 3 or 4 or not (condition for checking whether the number is semiprime or not).
Let's implement the above algorithm in a Java program. Brilliant Number Java ProgramObserve the implementation of the above algorithm. FileName: BrilliantNum.java Output: The number 15 is a brilliant number. The number 50 is not a brilliant number. The number 22 is not a brilliant number. Find Brilliant Numbers Within a RangeIn this approach, we will be using a sieve to find the brilliant numbers within the given range. Take two prime numbers of the same digits and find their product. The product is going to be a brilliant number. Suppose, we want to find the brilliant numbers that are present within the range 1 to 200. Observe the following algorithm. Step 1: Compute the sieve to find the prime numbers between 1 to 20. Step 2: Filter out the prime numbers and store them in an array or an ArrayList, which is al in our case. Step 3: Start a loop i = 0 to s  1, where s is the total size of the array Step 4: Within the loop started in step 3, start another loop j = I + 1 to size. Step 5: Ensure that the digit count of the number pointed by i is equal to the digit count of number pointed by j. Step 6: Find the product of the numbers pointed by the loop variables I and j. If the product is greater than the number 200, discard it; otherwise, keep it. Let's implement the above algorithm in a Java Program. FileName: BrilliantNum1.java Output: The brilliant numbers that lie within the range 1 to 200 are: 4 6 9 10 14 15 21 25 35 49 121 143 169 187
Next TopicSort Elements by Frequency in Java
