Numbers with prime frequencies greater than or equal to k

Given an array, find elements which appears prime number of times in the array with minimum k frequency (frequency >= k).

Examples :

Input : int[] arr = { 11, 11, 11, 23, 11, 37, 51, 
                      37, 37, 51, 51, 51, 51 };
        k = 2
Output : 37, 51
Explanation :
11's count is 4, 23 count 1, 37 count 3, 51 count 5. 
37 and 51 are two number that appear prime number of
time and frequencies greater than or equal to k.

Input : int[] arr = { 11, 22, 33 } min Occurrence = 1
Output : -1
None of the count is prime number of times

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach :
1. Create a Map which holds the number as Key and value as its occurrences in the input array.
2. Iterate the Map keys and look for the values corresponding to their keys, return the key which
has minimum value fulfilling condition key’s value is a prime number and >= min occurrence provided
as input.

C++

// C++ code to find number  
// occurring prime number  
// of times with frequency >= k 
#include <bits/stdc++.h> 
using namespace std; 
  
// Check if the number of  
// occurrences are primes 
// or not 
bool isPrime(int n) 
{ 
    // Corner case 
    if (n <= 1) return false; 
  
    // Check from 2 to n-1 
    for (int i = 2; i < n; i++) 
        if (n % i == 0) 
            return false; 
  
    return true; 
} 
  
// Function to find number 
// with prime occurrences 
void primeOccurences(int arr[], int k) 
{ 
    unordered_map<int, int> map; 
      
    // Insert values and 
    // their frequencies 
    for (int i = 0; i < 12; i++)  
        map[arr[i]]++; 
  
    // Traverse map and find 
    // elements with prime  
    // frequencies and frequency  
    // at least k 
    for (auto x : map)  
    { 
        if (isPrime(x.second) &&  
                    x.second >= k) 
            cout << x.first << endl; 
    } 
} 
  
// Driver code 
int main() 
{ 
    int arr[] = {11, 11, 11, 23,  
                 11, 37, 37, 51,  
                 51, 51, 51, 51}; 
    int k = 2; 
  
    primeOccurences(arr, k); 
    return 0; 
} 
  
// This code is contributed by 
// Manish Shaw(manishshaw1) 

Java

// Java code to find number occurring prime 
// number of times with frequency >= k 
import java.util.*; 
  
public class PrimeNumber { 
  
    // Function to find number with prime occurrences 
    static void primeOccurences(int[] arr, int k) 
    { 
        Map<Integer, Integer> map = new HashMap<>(); 
  
        // Insert values and their frequencies 
        for (int i = 0; i < arr.length; i++) { 
            int val = arr[i]; 
  
            int freq; 
            if (map.containsKey(val)) { 
                freq = map.get(val); 
                freq++; 
            } 
            else
                freq = 1; 
            map.put(val, freq); 
        } 
  
        // Traverse map and find elements with 
        // prime frequencies and frequency at 
        // least k 
        for (Map.Entry<Integer, Integer> entry :  
                               map.entrySet()) { 
            int value = entry.getValue(); 
            if (isPrime(value) && value >= k) 
                System.out.println(entry.getKey()); 
        } 
    } 
  
    // Check if the number of occurrences 
    // are primes or not 
    private static boolean isPrime(int n) 
    { 
  
        if ((n > 2 && n % 2 == 0) || n == 1)  
            return false;         
  
        for (int i = 3; i <= (int)Math.sqrt(n); 
             i += 2) { 
            if (n % i == 0)  
                return false;             
        } 
        return true; 
    } 
  
    // Driver code 
    public static void main(String[] args) 
    { 
        int[] arr = { 11, 11, 11, 23, 11, 37, 
                      37, 51, 51, 51, 51, 51 }; 
        int k = 2; 
  
        primeOccurences(arr, k); 
    } 
} 

Python3

# Python3 code to find number  
# occurring prime number of 
# times with frequency >= k 
  
# Function to find number  
# with prime occurrences 
def primeOccurences(arr, k): 
    map = {} 
  
    # Insert values and their frequencies 
    for val in arr: 
        freq = 0
          
        if val in map : 
            freq = map[val] 
            freq += 1
              
        else : 
            freq = 1
        map[val] = freq 
  
    # Traverse map and find elements  
    # with prime frequencies and  
    # frequency at least k 
    for entry in map : 
        value = map[entry] 
          
        if isPrime(value) and value >= k: 
            print(entry) 
  
# Check if the number of occurrences 
# are primes or not 
def isPrime(n): 
  
    if (n > 2 and not n % 2) or n == 1: 
        return False     
  
    for i in range(3, int(n**0.5 + 1), 2): 
        if not n % i: 
            return False
              
    return True
  
  
# Driver code 
  
arr = [ 11, 11, 11, 23, 11, 37, 
        37, 51, 51, 51, 51, 51 ] 
k = 2
  
primeOccurences(arr, k) 
  
  
# This code is contributed by Ansu Kumari. 

C#

// C# code to find number  
// occurring prime number 
// of times with frequency >= k 
using System; 
using System.Collections.Generic; 
  
class GFG 
{ 
  
    // Function to find number 
    // with prime occurrences 
    static void primeOccurences(int[] arr,  
                                int k) 
    { 
        Dictionary<int, int> map =  
                   new Dictionary<int, int>(); 
          
        // Insert values and 
        // their frequencies 
        for (int i = 0; i < arr.Length; i++)  
        { 
            int val = arr[i]; 
  
            int freq; 
            if (map.ContainsKey(val))  
            { 
                freq = map[val]; 
                freq++; 
                map.Remove(val); 
            } 
            else
                freq = 1; 
            map.Add(val, freq); 
        } 
  
        // Traverse map and find elements 
        // with prime frequencies and  
        // frequency atleast k 
        foreach (KeyValuePair<int, int>  
                           pair in map) 
        { 
            int value = pair.Value; 
            if (isPrime(value) &&  
                        value >= k) 
                Console.WriteLine(pair.Key); 
        } 
    } 
  
    // Check if the number 
    // of occurrences 
    // are primes or not 
    static bool isPrime(int n) 
    { 
        if ((n > 2 &&  
             n % 2 == 0) || n == 1)  
            return false;      
  
        for (int i = 3;  
                 i <= (int)Math.Sqrt(n);  
                 i += 2)  
            { 
                if (n % i == 0)  
                    return false;          
            } 
        return true; 
    } 
  
    // Driver code 
    static void Main() 
    { 
        int[] arr = new int[]{11, 11, 11, 23, 11, 37, 
                              37, 51, 51, 51, 51, 51}; 
        int k = 2; 
  
        primeOccurences(arr, k); 
    } 
} 
  
// This code is contributed by  
// Manish Shaw(manishshaw1) 

Output :

37
51

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My Personal Notes

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

C++

Java

Python3

C#

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