eGYDFG - Online Java Compiler & Debugging Tool

import java.util.*;

public class Main {

    static HashMap<Long, Long> primeFactors(long n) {
        HashMap<Long, Long> map = new HashMap<>();

        while (n % 2 == 0) {
            map.put(2L, map.getOrDefault(2L, 0L) + 1);
            n /= 2;
        }

        long lim = (long) Math.sqrt(n);
        for (long i = 3; i <= lim; i += 2) {
            while (n % i == 0) {
                map.put(i, map.getOrDefault(i, 0L) + 1);
                n /= i;
            }
        }

        if (n > 2) map.put(n, map.getOrDefault(n, 0L) + 1);

        return map;
    }

    public static void main(String[] args) {
        long n = 18;
        HashMap<Long, Long> res = primeFactors(n);
        for (Map.Entry<Long, Long> e : res.entrySet()) {
            System.out.println(e.getKey() + " " + e.getValue());
        }
    }
}