K-th Smallest Prime Fraction

You are given a sorted integer array arr containing 1 and prime numbers, where all the integers of arr are unique. You are also given an integer k.

For every i and j where 0 <= i < j < arr.length, we consider the fraction arr[i] / arr[j].

Return the k<sup>th</sup> smallest fraction considered. Return your answer as an array of integers of size 2, where answer[0] == arr[i] and answer[1] == arr[j].

LeetCode Problem - 786

class Solution {
    // Method to find the kth smallest prime fraction
    public int[] kthSmallestPrimeFraction(int[] arr, int k) {
        // List to store fractions
        List<Double> al = new ArrayList<>();
        // Map to store fractions and their string representations
        Map<Double, String> mp = new HashMap<>();

        // Generate all possible fractions from the array elements
        for(int i = 0; i < arr.length; i++) {
            for(int j = i + 1; j < arr.length; j++) {
                double x = (double) arr[i], y = (double) arr[j];
                double fraction = x / y;
                al.add(fraction);

                String temp = arr[i] + "/" + arr[j];
                mp.put(fraction, temp);
            }
        }

        // Sort the list of fractions
        Collections.sort(al);
        // Get the kth smallest fraction
        double answerFraction = al.get(k - 1);

        // Get the string representation of the kth smallest fraction
        String answerString = mp.get(answerFraction);
        // Split the string to get the numerator and denominator
        String[] splitAns = answerString.split("/");

        // Parse the numerator and denominator to integers
        int a = Integer.parseInt(splitAns[0]);
        int b = Integer.parseInt(splitAns[1]);

        // Return the kth smallest fraction as an array
        return new int[] {a, b};
    }
}