PrimeFibonacci.java

import java.util.*;

public class PrimeFibonacci {
    public static void main(String[] args) {
        Scanner abhi = new Scanner(System.in);
        int firstNumber;
        int secondNumber;
        long result;
        firstNumber = abhi.nextInt();
        secondNumber = abhi.nextInt();
        result = solvePrimeFibonacci(firstNumber, secondNumber);
        System.out.println(result);
        abhi.close();
    }
    
    public static long solvePrimeFibonacci(int startRange, int endRange) {
        // Idhar humko prime numbers between startRange and endRange Nikalne hai
        List<Integer> firstPrimeList = findPrimesInRange(startRange, endRange);
        
        // Phir saare possible unique combinations
        Set<Integer> combinationSet = generateAllCombinations(firstPrimeList);
        // Phir un combinations me se prime numbers nikalne hain
        List<Integer> secondPrimeList = findPrimesFromSet(combinationSet);
        
        int smallestPrime = Collections.min(secondPrimeList);
        int largestPrime = Collections.max(secondPrimeList);
        int primeCount = secondPrimeList.size();
        
        return generateFibonacciLastNumber(smallestPrime, largestPrime, primeCount);
    }
    
    public static boolean isPrime(int number) {
        if (number < 2) return false;
        if (number == 2) return true;
        if (number % 2 == 0) return false;
        
        for (int divisor = 3; divisor * divisor <= number; divisor += 2) {
            if (number % divisor == 0) {
                return false;
            }
        }
        return true;
    }
    
    public static List<Integer> findPrimesInRange(int startRange, int endRange) {
        List<Integer> primeList = new ArrayList<>();
        
        for (int currNumber = startRange; currNumber <= endRange; currNumber++) {
            if (isPrime(currNumber)) {
                primeList.add(currNumber);
            }
        }
        
        return primeList;
    }
    
    public static Set<Integer> generateAllCombinations(List<Integer> primeList) {
        Set<Integer> combinationSet = new HashSet<>();
        int listSize = primeList.size();
        
        for (int firstIndex = 0; firstIndex < listSize; firstIndex++) {
            for (int secondIndex = 0; secondIndex < listSize; secondIndex++) {
                if (firstIndex != secondIndex) {
                    String firstPrime = String.valueOf(primeList.get(firstIndex));
                    String secondPrime = String.valueOf(primeList.get(secondIndex));
                    String combinedNumber = firstPrime + secondPrime;
                    
                    try {
                        int combinationValue = Integer.parseInt(combinedNumber);
                        combinationSet.add(combinationValue);
                    } catch (NumberFormatException exception) {
                        continue;
                    }
                }
            }
        }
        
        return combinationSet;
    }
    
    public static List<Integer> findPrimesFromSet(Set<Integer> combinationSet) {
        List<Integer> primeList = new ArrayList<>();
        
        for (int currNumber : combinationSet) {
            if (isPrime(currNumber)) {
                primeList.add(currNumber);
            }
        }
        
        return primeList;
    }
    
    public static long generateFibonacciLastNumber(int firstTerm, int secondTerm, int termCount) {
        if (termCount == 1) return firstTerm;
        if (termCount == 2) return secondTerm;
        
        long prevTerm = firstTerm;
        long currTerm = secondTerm;
        long nextTerm = 0;
        
        for (int termIndex = 3; termIndex <= termCount; termIndex++) {
            nextTerm = prevTerm + currTerm;
            prevTerm = currTerm;
            currTerm = nextTerm;
        }
        
        return currTerm;
    }
}