Maximize frequency sum of K chosen characters from given string Last Updated : 07 Oct, 2022 Summarize Comments Improve Suggest changes Share Like Article Like Report Given a positive integer K and a string S consisting of N characters, the task is to maximize the sum of the frequencies of exactly K chosen characters from the given string. Examples: Input: K - 3, S = ”GEEKSFORGEEKS”Output: 12Explanation:Choose the character E from the given string S, the sum of frequency of 3 E's is 3*4 = 12, which is the maximum. Input: K = 10, S = ”GEEKSFORGEEKS”Output: 28 Approach: The given problem can be solved by using the Greedy Approach by choosing those K characters having the higher frequencies. Follow the steps below to solve the problem: Initialize a variable, say sum to 0 that stores the resultant sum of frequencies of exactly K chosen characters from the string S.Find the frequencies of each character in the string S and store it in an auxiliary array, say freq[].Sort the array freq[] in descending order.Traverse the array freq[] and perform the following:If the current frequency is less than K, then add freq[i]*freq[i] to the variable sum as it maximizes the resultant sum and decrements the value of freq[i] from K as freq[i] characters are chosen.Otherwise, add the value of K*freq[i] to the variable sum and break out of the loop as K characters have been chosen.After completing the above steps, print the value of the sum as the result. Below is the implementation of the above approach: C++ // C++ program for the above approach #include <bits/stdc++.h> using namespace std; // Function to find the maximum sum of // frequencies of the exactly K chosen // characters from the string S int maximumSum(string S, int N, int K) { // Stores the resultant maximum sum int sum = 0; // Stores the frequency of array // elements int freq[256] = { 0 }; // Find the frequency of character for (int i = 0; i < N; i++) { freq[int(S[i])]++; } // Sort the frequency array in the // descending order sort(freq, freq + 256, greater<int>()); // Iterate to choose K elements greedily for (int i = 0; i < 256; i++) { // If the freq[i] cards are // chosen if (K > freq[i]) { sum += freq[i] * freq[i]; K -= freq[i]; } // K cards have been picked else { sum += freq[i] * K; break; } } // Return the resultant sum return sum; } // Driver Code int main() { string S = "GEEKSFORGEEKS"; int K = 10; int N = S.length(); cout << maximumSum(S, N, K); return 0; } Java // Java program for the above approach import java.util.*; class GFG { // Function to find the maximum sum of // frequencies of the exactly K chosen // characters from the String S static int maximumSum(String S, int N, int K) { // Stores the resultant maximum sum int sum = 0; // Stores the frequency of array // elements Integer []freq = new Integer[256]; Arrays.fill(freq, 0); // Find the frequency of character for(int i = 0; i < N; i++) { freq[(int)S.charAt(i)] += 1; } // Sort the frequency array in the // descending order Arrays.sort(freq, Collections.reverseOrder()); // Iterate to choose K elements greedily for(int i = 0; i < 256; i++) { // If the freq[i] cards are // chosen if (K > freq[i]) { sum += freq[i] * freq[i]; K -= freq[i]; } // K cards have been picked else { sum += freq[i] * K; break; } } // Return the resultant sum return sum; } // Driver Code public static void main(String args[]) { String S = "GEEKSFORGEEKS"; int K = 10; int N = S.length(); System.out.print(maximumSum(S, N, K)); } } // This code is contributed by ipg2016107 Python3 # Python3 program for the above approach # Function to find the maximum sum of # frequencies of the exactly K chosen # characters from the string S def maximumSum(S, N, K): # Stores the resultant maximum sum sum = 0 # Stores the frequency of array # elements freq = [0] * 256 # Find the frequency of character for i in range(N): freq[ord(S[i])] += 1 # Sort the frequency array in the # descending order freq = sorted(freq)[::-1] # Iterate to choose K elements greedily for i in range(256): # If the freq[i] cards are # chosen if (K > freq[i]): sum += freq[i] * freq[i] K -= freq[i] # K cards have been picked else: sum += freq[i] * K break # Return the resultant sum return sum # Driver Code if __name__ == '__main__': S = "GEEKSFORGEEKS" K = 10 N = len(S) print(maximumSum(S, N, K)) # This code is contributed by mohit kumar 29 C# // C# program for the above approach using System; using System.Collections.Generic; class GFG{ // Function to find the maximum sum of // frequencies of the exactly K chosen // characters from the string S static int maximumSum(string S, int N, int K) { // Stores the resultant maximum sum int sum = 0; // Stores the frequency of array // elements int []freq = new int[256]; Array.Clear(freq, 0, 256); // Find the frequency of character for(int i = 0; i < N; i++) { freq[(int)S[i]]++; } // Sort the frequency array in the // descending order Array.Sort(freq); Array.Reverse(freq); // Iterate to choose K elements greedily for(int i = 0; i < 256; i++) { // If the freq[i] cards are // chosen if (K > freq[i]) { sum += freq[i] * freq[i]; K -= freq[i]; } // K cards have been picked else { sum += freq[i] * K; break; } } // Return the resultant sum return sum; } // Driver Code public static void Main() { string S = "GEEKSFORGEEKS"; int K = 10; int N = S.Length; Console.Write(maximumSum(S, N, K)); } } // This code is contributed by ipg2016107 JavaScript <script> // JavaScript program for the above approach // Function to find the maximum sum of // frequencies of the exactly K chosen // characters from the string S function maximumSum(S, N, K) { // Stores the resultant maximum sum let sum = 0; // Stores the frequency of array // elements let freq = Array.from({length: 256}, (_, i) => 0); // Find the frequency of character for(let i = 0; i < N; i++) { freq[S[i].charCodeAt()]++; } // Sort the frequency array in the // descending order freq.sort((a, b) => b - a); // Iterate to choose K elements greedily for(let i = 0; i < 256; i++) { // If the freq[i] cards are // chosen if (K > freq[i]) { sum += freq[i] * freq[i]; K -= freq[i]; } // K cards have been picked else { sum += freq[i] * K; break; } } // Return the resultant sum return sum; } // Driver Code let S = "GEEKSFORGEEKS"; let K = 10; let N = S.length; document.write(maximumSum(S.split(''), N, K)) </script> Output: 28 Time Complexity: O(N)Auxiliary Space: O(256) Comment More infoAdvertise with us Next Article Maximize frequency sum of K chosen characters from given string S sam_2200 Follow Improve Article Tags : Strings Greedy Mathematical DSA frequency-counting +1 More Practice Tags : GreedyMathematicalStrings Similar Reads DSA Tutorial - Learn Data Structures and Algorithms DSA (Data Structures and Algorithms) is the study of organizing data efficiently using data structures like arrays, stacks, and trees, paired with step-by-step procedures (or algorithms) to solve problems effectively. Data structures manage how data is stored and accessed, while algorithms focus on 7 min read Quick Sort QuickSort is a sorting algorithm based on the Divide and Conquer that picks an element as a pivot and partitions the given array around the picked pivot by placing the pivot in its correct position in the sorted array. It works on the principle of divide and conquer, breaking down the problem into s 12 min read Merge Sort - Data Structure and Algorithms Tutorials Merge sort is a popular sorting algorithm known for its efficiency and stability. It follows the divide-and-conquer approach. It works by recursively dividing the input array into two halves, recursively sorting the two halves and finally merging them back together to obtain the sorted array. Merge 14 min read Data Structures Tutorial Data structures are the fundamental building blocks of computer programming. They define how data is organized, stored, and manipulated within a program. Understanding data structures is very important for developing efficient and effective algorithms. What is Data Structure?A data structure is a st 2 min read Bubble Sort Algorithm Bubble Sort is the simplest sorting algorithm that works by repeatedly swapping the adjacent elements if they are in the wrong order. This algorithm is not suitable for large data sets as its average and worst-case time complexity are quite high.We sort the array using multiple passes. After the fir 8 min read Breadth First Search or BFS for a Graph Given a undirected graph represented by an adjacency list adj, where each adj[i] represents the list of vertices connected to vertex i. Perform a Breadth First Search (BFS) traversal starting from vertex 0, visiting vertices from left to right according to the adjacency list, and return a list conta 15+ min read Binary Search Algorithm - Iterative and Recursive Implementation Binary Search Algorithm is a searching algorithm used in a sorted array by repeatedly dividing the search interval in half. The idea of binary search is to use the information that the array is sorted and reduce the time complexity to O(log N). Binary Search AlgorithmConditions to apply Binary Searc 15 min read Insertion Sort Algorithm Insertion sort is a simple sorting algorithm that works by iteratively inserting each element of an unsorted list into its correct position in a sorted portion of the list. It is like sorting playing cards in your hands. You split the cards into two groups: the sorted cards and the unsorted cards. T 9 min read Array Data Structure Guide In this article, we introduce array, implementation in different popular languages, its basic operations and commonly seen problems / interview questions. An array stores items (in case of C/C++ and Java Primitive Arrays) or their references (in case of Python, JS, Java Non-Primitive) at contiguous 4 min read Sorting Algorithms A Sorting Algorithm is used to rearrange a given array or list of elements in an order. For example, a given array [10, 20, 5, 2] becomes [2, 5, 10, 20] after sorting in increasing order and becomes [20, 10, 5, 2] after sorting in decreasing order. There exist different sorting algorithms for differ 3 min read Like