Count of isogram strings in given array of strings with length at least K

Given an array arr[] containing N strings and an integer K, the task is to find the number of strings which are isograms and at least of length K.

Examples:

Input: arr[] = {“abcd”, “der”, “erty”}, K = 4
Output: 2
Explanation: All given strings are isograms, but only “abcd” and “erty” are of length at least K. Hence count is 2

Input: arr[] = {“ag”, “bka”, “lkmn”, “asdfg”}, K = 2
Output: 4
Explanation: All the strings are isograms and each strings is of length >=K. Hence count is 4.

Approach: This problem can be solved by storing frequencies of all the characters or by using a Set data structure. A string is an isogram if no letter in that string appears more than once. Follow the steps below to solve the given problem. 

• Traverse the array of strings arr[], and for each string
• Create a frequency map of characters.
• Wherever any character has a frequency greater than 1, or if the length of the string is less than K, skip the current string.
• Otherwise, if no character has a frequency more than 1, and if the length of the string is less than K, increment the count of the answer.
• Print the count stored in the answer when all the strings are traversed.

Below is the implementation of the above approach.

C++

// C++ code for the above approach
#include <bits/stdc++.h>
using namespace std;

// Function to check if a string
// is an isogram or not
bool isIsogram(string s)
{
    // To store the frequencies
    vector<int> freq(26, 0);

    for (char c : s) {
        freq++;

        if (freq > 1) {
            return false;
        }
    }

    return true;
}

// Function to check if array arr contains
// all isograms or not
int allIsograms(vector<string>& arr, int K)
{
    int ans = 0;
    for (string x : arr) {
        if (isIsogram(x) && x.length() >= K) {
            ans++;
        }
    }

    return ans;
}

// Driver Code
int main()
{
    vector<string> arr = { "abcd", "der", "erty" };
    int K = 4;

    // Function call and printing the answer
    cout << allIsograms(arr, K);
}

Java

// Java code for the above approach
import java.io.*;

class GFG {

    // Function to check if a string
    // is an isogram or not
    static boolean isIsogram(String s)
    {
        // To store the frequencies
        int[] freq = new int[26];

        for (int i = 0; i < s.length(); i++) {
            char c = s.charAt(i);
            freq++;

            if (freq > 1) {
                return false;
            }
        }

        return true;
    }

    // Function to check if array arr contains
    // all isograms or not
    static int allIsograms(String[] arr, int K)
    {
        int ans = 0;
        for (String x : arr) {
            if (isIsogram(x) && x.length() >= K) {
                ans++;
            }
        }

        return ans;
    }

    // Driver Code
    public static void main(String[] args)
    {
        String arr[] = { "abcd", "der", "erty" };
        int K = 4;

        // Function call and printing the answer

        System.out.println(allIsograms(arr, K));
    }
}

// This code is contributed by Potta Lokesh

Python3

# Python code for the above approach

# Function to check if a string
# is an isogram or not
def isIsogram (s):

    # To store the frequencies
    freq = [0] * 26

    for c in s:
        freq[ord(c) - ord("a")] += 1

        if (freq[s.index(c)] > 1):
            return False

    return True

# Function to check if array arr contains
# all isograms or not
def allIsograms (arr, K):
    ans = 0
    for x in arr:
        if isIsogram(x) and len(x) >= K:
            ans += 1

    return ans


# Driver Code
arr = ["abcd", "der", "erty"]
K = 4

# Function call and printing the answer
print(allIsograms(arr, K))

# This code is contributed by Saurabh jaiswal

C#

// C# code for the above approach
using System;

class GFG{

// Function to check if a string
// is an isogram or not
static bool isIsogram(string s)
{

    // To store the frequencies
    int[] freq = new int[26];

    for(int i = 0; i < s.Length; i++)
    {
        char c = s[i];
        freq++;

        if (freq > 1)
        {
            return false;
        }
    }
    return true;
}

// Function to check if array arr contains
// all isograms or not
static int allIsograms(string[] arr, int K)
{
    int ans = 0;
    foreach(string x in arr)
    {
        if (isIsogram(x) && x.Length >= K)
        {
            ans++;
        }
    }
    return ans;
}

// Driver Code
public static void Main(string[] args)
{
    string[] arr = { "abcd", "der", "erty" };
    int K = 4;

    // Function call and printing the answer
    Console.WriteLine(allIsograms(arr, K));
}
}

// This code is contributed by ukasp

Javascript

<script>
    // JavaScript code for the above approach

    // Function to check if a string
    // is an isogram or not
    const isIsogram = (s) => {

        // To store the frequencies
        let freq = new Array(26).fill(0);

        for (let c in s) {
            freq[s.charCodeAt(c) - "a".charCodeAt(0)]++;

            if (freq > 1) {
                return false;
            }
        }

        return true;
    }

    // Function to check if array arr contains
    // all isograms or not
    const allIsograms = (arr, K) => {
        let ans = 0;
        for (let x in arr) {
            if (isIsogram(x) && arr[x].length >= K) {
                ans++;
            }
        }

        return ans;
    }

    // Driver Code
    let arr = ["abcd", "der", "erty"];
    let K = 4;

    // Function call and printing the answer
    document.write(allIsograms(arr, K));

    // This code is contributed by rakeshsahni
</script>

Output

2

Time Complexity: O(N*M), where N is the size of the array and M is the size of the longest string.

Auxiliary Space: O(1).