Check whether count of distinct characters in a string is Prime or not

Given a string of lowercase English alphabets. The task is to check if the count of distinct characters in the string is prime or not.

Examples:

Input : str = "geeksforgeeks"
Output :Yes
Explanation: The number of distinct characters in the
string is 7, and 7 is a prime number.

Input : str ="geeks"
Output : No 

In this problem first we have to count the distinct characters in the string. We will use a map to store the frequency of each alphabets. The next step is to count the number of distinct characters, and check whether the number is prime or not . 

If the number is prime we will print Yes, else No. 

Below is the implementation of the above approach:  

C++

// C++ program to check whether count of
// distinct characters in a string
// is Prime or not
#include <bits/stdc++.h>
using namespace std;

// Find whether a number is prime or not
bool isPrime(int n)
{
    int i;

    // 1 is not prime
    if (n == 1)
        return false;

    // check if there is any factor or not
    for (i = 2; i <= sqrt(n); i++) {
        if (n % i == 0)
            return false;
    }
    return true;
}

// Count the distinct characters in a string
int countDistinct(string s)
{
    // create a map to store the
    // frequency of characters
    unordered_map<char, int> m;

    // traverse the string
    for (int i = 0; i < s.length(); i++) {
        // increase the frequency of character
        m[s[i]]++;
    }

    return m.size();
}

// Driver code
int main()
{
    string str = "geeksforgeeks";

    if (isPrime(countDistinct(str)))
        cout << "Yes" << endl;
    else
        cout << "No" << endl;

    return 0;
}

Java

// Java program to check whether count of
// distinct characters in a string
// is Prime or not
import java.util.*;

class GFG
{
    // Find whether a number is prime or not
    static boolean isPrime(int n)
    {
        int i;

        // 1 is not prime
        if (n == 1)
            return false;

        // check if there is any factor or not
        for (i = 2; i <= Math.sqrt(n); i++)
        {
            if (n % i == 0)
                return false;
        }
        return true;
    }

    // Count the distinct characters in a string
    static int countDistinct(String s)
    {
        // create a map to store the
        // frequency of characters
        Set<Character> m = new HashSet<Character>();

        // traverse the string
        for (int i = 0; i < s.length(); i++)
        {

            // increase the frequency of character
            m.add(s.charAt(i));

        }

        return m.size();
    }

    // Driver code
    public static void main(String []args)
    {
        String str = "geeksforgeeks";

        if (isPrime(countDistinct(str)))
            System.out.println("Yes");
        else
            System.out.println("No");
    }
}

// This code is contributed by ihritik

Python3

# Python 3 program to check whether
# count of distinct characters in a
# string is Prime or not

# from math library import
# sqrt method
from math import sqrt

# Find whether a number
# is prime or not
def isPrime(n) :

    # 1 is not prime
    if n == 1 :
        return False

    # check if there is any
    # factor or not
    for i in range(2, int(sqrt(n)) + 1) :

        if n % i == 0 :
            return False

    return True

# Count the distinct characters
# in a string
def countDistinct(s) :

    # create a dictionary to store
    # the frequency of characters
    m = {}

    # dictionary with keys and its
    # initialize with value 0
    m = m.fromkeys(s, 0)

    # traverse the string
    for i in range(len(s)) :

        # increase the frequency
        # of character
        m[s[i]] += 1

    return len(m.keys())

# Driver code
if __name__ == "__main__" :

    str = "geeksforgeeks"

    if isPrime(countDistinct(str)) :
        print("Yes")
    else :
        print("No")

# This code is contributed
# by ANKITRAI1

C#

// C# program to check whether count of
// distinct characters in a string
// is Prime or not
using System;
using System.Collections.Generic;

class GFG
{
    // Find whether a number is prime or not
    static bool isPrime(int n)
    {
        int i;

        // 1 is not prime
        if (n == 1)
            return false;

        // check if there is any factor or not
        for (i = 2; i <= Math.Sqrt(n); i++)
        {
            if (n % i == 0)
                return false;
        }
        return true;
    }

    // Count the distinct characters in a string
    static int countDistinct(String s)
    {
        // create a map to store the
        // frequency of characters
        HashSet<char> m = new HashSet<char>();

        // traverse the string
        for (int i = 0; i < s.Length; i++)
        {

            // increase the frequency of character
            m.Add(s[i]);

        }

        return m.Count;
    }

    // Driver code
    public static void Main(String []args)
    {
        String str = "geeksforgeeks";

        if (isPrime(countDistinct(str)))
            Console.WriteLine("Yes");
        else
            Console.WriteLine("No");
    }
}

// This code has been contributed by 29AjayKumar

Javascript

<script>

// Javascript program to check whether count of
// distinct characters in a string
// is Prime or not

// Find whether a number is prime or not
function isPrime(n)
{
    var i;

    // 1 is not prime
    if (n == 1)
        return false;

    // check if there is any factor or not
    for (i = 2; i <= Math.sqrt(n); i++) {
        if (n % i == 0)
            return false;
    }
    return true;
}

// Count the distinct characters in a string
function countDistinct(s)
{
    // create a map to store the
    // frequency of characters
    var m = new Map();

    // traverse the string
    for (var i = 0; i < s.length; i++) {
        // increase the frequency of character
        if(m.has(s[i]))
        {
            m.set(s[i], m[s[i]]+1);
        }
        else
        {
            m.set(s[i],1);
        }
    }

    return m.size;
}

// Driver code
var str = "geeksforgeeks";
if (isPrime(countDistinct(str)))
    document.write( "Yes" );
else
    document.write( "No" );

// This code is contributed by rutvik_56.
</script>

Output

Yes

Complexity Analysis:

• Time Complexity: O((len(str))^1/2)
• Auxiliary Space: O(len(str))

Method 2: Using Counter function:

• Count the frequencies of all elements using Counter function and number of keys of this frequency dictionary gives the count and check whether it is prime or not.

Below is the implementation:

C++

// Cpp program for the above approach
#include <iostream>
#include <unordered_map>
#include <cmath>

using namespace std;

bool isPrime(int n) {
    if (n == 1) { // 1 is not prime
        return false;
    }

    // Check if there is any factor or not
    for (int i = 2; i <= sqrt(n); i++) {
        if (n % i == 0) {
            return false;
        }
    }

    return true;
}

bool countDis(string str) {

    // Stores all frequencies
    unordered_map<char, int> freq;

    for (int i = 0; i < str.length(); i++) {
        char ch = str[i];
        freq[ch]++;
    }

    // Return the size of the freq object
    if (isPrime(freq.size())) {
        return true;
    } else {
        return false;
    }
}

// Driver code
int main() {
    string S = "geeksforgeeks";
    cout << countDis(S) << endl;
    return 0;
}


//This code is contributed by shivamsharma215
//Output is 1 i.e. True

Java

import java.util.*;

public class Main {
    public static boolean isPrime(int n) {
        if (n == 1) { // 1 is not prime
            return false;
        }

        // Check if there is any factor or not
        for (int i = 2; i <= Math.sqrt(n); i++) {
            if (n % i == 0) {
                return false;
            }
        }

        return true;
    }

    public static boolean countDis(String str) {

        // Stores all frequencies
        Map<Character, Integer> freq = new HashMap<>();

        for (int i = 0; i < str.length(); i++) {
            char ch = str.charAt(i);
            freq.put(ch, freq.getOrDefault(ch, 0) + 1);
        }

        // Return the size of the freq object
        if (isPrime(freq.keySet().size())) {
            return true;
        } else {
            return false;
        }
    }

    // Driver code
    public static void main(String[] args) {
        String S = "geeksforgeeks";
        System.out.println(countDis(S));
    }
}

Python3

# Python program for the above approach
from collections import Counter
from math import sqrt as sqrt


def isPrime(n):

    # 1 is not prime
    if n == 1:
        return False

    # check if there is any
    # factor or not
    for i in range(2, int(sqrt(n)) + 1):

        if n % i == 0:
            return False

    return True

# Function to count the number of distinct
# characters present in the string
# str and check whether it is prime


def countDis(str):

    # Stores all frequencies
    freq = Counter(str)

    # Return the size of the freq dictionary
    if(isPrime(len(freq))):
        return True
    else:
        return False


# Driver Code
if __name__ == "__main__":

        # Given string S
    S = "geeksforgeeks"

    print(countDis(S))

# This code is contributed by vikkycirus

C#

using System;
using System.Collections.Generic;
using System.Linq;

public class Gfg
{
    public static bool isPrime(int n)
    {
        if (n == 1) // 1 is not prime
        {
            return false;
        }

        // Check if there is any factor or not
        for (int i = 2; i <= Math.Sqrt(n); i++)
        {
            if (n % i == 0)
            {
                return false;
            }
        }

        return true;
    }

    public static bool countDis(string str)
    {
        // Stores all frequencies
        Dictionary<char, int> freq = new Dictionary<char, int>();

        foreach (char ch in str)
        {
            if (freq.ContainsKey(ch))
            {
                freq[ch]++;
            }
            else
            {
                freq.Add(ch, 1);
            }
        }

        // Return the size of the freq object
        if (isPrime(freq.Count))
        {
            return true;
        }
        else
        {
            return false;
        }
    }

    public static void Main()
    {
        string S = "geeksforgeeks";
        Console.WriteLine(countDis(S));
    }
}

Javascript

// Javacript program for the above approach
function isPrime(n) {
  if (n === 1) { // 1 is not prime
    return false;
  }

  // Check if there is any factor or not
  for (let i = 2; i <= Math.sqrt(n); i++) {
    if (n % i === 0) {
      return false;
    }
  }

  return true;
}

function countDis(str)
{

  // Stores all frequencies
  let freq = {};

  for (let i = 0; i < str.length; i++) {
    freq[str[i]] = (freq[str[i]] || 0) + 1;
  }

  // Return the size of the freq object
  if (isPrime(Object.keys(freq).length)) {
    return true;
  } else {
    return false;
  }
}

// Driver code
let S = "geeksforgeeks";
console.log(countDis(S));

// This code is contributed by codebraxnzt

Output

True

• Time Complexity: O((len(str))^1/2)
• Auxiliary Space: O(len(str))