Skip to content
Related Articles

Related Articles

Improve Article
Save Article
Like Article

Frequency of lexicographically Kth smallest character in the a string

  • Last Updated : 01 Jun, 2021

Given a string S of length N and an integer K, the task is to find the frequency of the lexicographically Kth smallest character present in the given string.

Examples:

Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.  To complete your preparation from learning a language to DS Algo and many more,  please refer Complete Interview Preparation Course.

In case you wish to attend live classes with experts, please refer DSA Live Classes for Working Professionals and Competitive Programming Live for Students.

Input: S = “geeksforgeeks”, K = 3
Output: 4
Explanation: The lexicographically 3rd smallest character in S is ‘e’. Frequency of ‘e’ in S = 4.



Input: S = “abcdabcd”, K = 4
Output: 2
Explanation: The lexicographically 4th smallest lexicographical character in S is ‘b’. Frequency of ‘b’ in S = 2.

Approach: The idea is to sort the string in ascending order of their ASCII values. Now, find the (K – 1)th character in the sorted string and find its frequency. Follow the steps below to solve the problem:

Below is the implementation of the approach:

C++




// C++ program for the above approach
 
#include <bits/stdc++.h>
using namespace std;
 
// Function to find the frequency of
// the lexicographically Kth smallest
// character
void KthCharacter(
  string S, int N, int K)
{
 
  // Convert the string to
  // array of characters
  char strarray[N + 1];
  strcpy(strarray, S.c_str());
 
  // Sort the array in ascending order
  sort(strarray, strarray + N);
 
  // Store the Kth character
  char ch = strarray[K - 1];
 
  // Store the frequency of
  // the K-th character
  int count = 0;
 
  // Count the frequency of
  // the K-th character
  for (auto c : strarray)
  {
    if (c == ch)
      count++;
  }
 
  // Print the count
  cout << count;
}
 
// Driver Code
int main()
{
  string S = "geeksforgeeks";
  int N = S.length();
  int K = 3;
 
  KthCharacter(S, N, K);
 
  return 0;
}
 
// This code is contributed by sanjoy_62.

Java




// Java program for the above approach
import java.io.*;
import java.util.*;
 
class GFG {
 
    // Function to find the frequency of
    // the lexicographically Kth smallest
    // character
    public static void KthCharacter(
        String S, int N, int K)
    {
        // Convert the string to
        // array of characters
        char strarray[] = S.toCharArray();
 
        // Sort the array in ascending order
        Arrays.sort(strarray);
 
        // Store the Kth character
        char ch = strarray[K - 1];
 
        // Store the frequency of
        // the K-th character
        int count = 0;
 
        // Count the frequency of
        // the K-th character
        for (char c : strarray) {
            if (c == ch)
                count++;
        }
 
        // Print the count
        System.out.println(count);
    }
 
    // Driver Code
    public static void main(String[] args)
    {
        String S = "geeksforgeeks";
        int N = S.length();
        int K = 3;
 
        KthCharacter(S, N, K);
    }
}

Python3




# Python program for the above approach
 
# Function to find the frequency of
# the lexicographically Kth smallest
# character
def KthCharacter(S, N, K):
   
    # Convert the string to
    # array of characters
    strarray = [char for char in S];
 
    # Sort the array in ascending order
    strarray.sort();
 
    # Store the Kth character
    ch = strarray[K - 1];
 
    # Store the frequency of
    # the K-th character
    count = 0;
 
    # Count the frequency of
    # the K-th character
    for c in strarray:
        if (c == ch):
            count += 1;
 
    # Prthe count
    print(count);
 
# Driver Code
if __name__ == '__main__':
    S = "geeksforgeeks";
    N = len(S);
    K = 3;
 
    KthCharacter(S, N, K);
 
# This code is contributed by 29AjayKumar

C#




// C# program to implement
// the above approach
using System;
class GFG
{
 
  // Function to find the frequency of
  // the lexicographically Kth smallest
  // character
  public static void KthCharacter(
    string S, int N, int K)
  {
 
    // Convert the string to
    // array of characters
    char[] strarray = S.ToCharArray();
 
    // Sort the array in ascending order
    Array.Sort(strarray);
 
    // Store the Kth character
    char ch = strarray[K - 1];
 
    // Store the frequency of
    // the K-th character
    int count = 0;
 
    // Count the frequency of
    // the K-th character
    foreach (char c in strarray)
    {
      if (c == ch)
        count++;
    }
 
    // Print the count
    Console.Write(count);
  }
 
  // Driver Code
  public static void Main()
  {
    string S = "geeksforgeeks";
    int N = S.Length;
    int K = 3;
 
    KthCharacter(S, N, K);
  }
}
 
// This code is contributed by splevel62.

Javascript




<script>
 
// Javascript program for the above approach
 
// Function to find the frequency of
// the lexicographically Kth smallest
// character
function KthCharacter(S, N, K)
{
 
    // Convert the string to
    // array of characters
    var strarray = S.split('');
     
    strarray.sort();
     
    // Store the Kth character
    var ch = strarray[K - 1];
     
    // Store the frequency of
    // the K-th character
    var count = 0;
     
    // Count the frequency of
    // the K-th character
    strarray.forEach(c => {
        if (c == ch)
            count++;
    });
     
    // Print the count
    document.write(count);
}
 
// Driver Code
var S = "geeksforgeeks";
var N = S.length;
var K = 3;
 
KthCharacter(S, N, K);
 
// This code is contributed by famously
 
</script>
Output: 
4

 

Time Complexity: O(N*log N)
Auxiliary Space: O(N)




My Personal Notes arrow_drop_up
Recommended Articles
Page :