Find maximum occurring character in a string

Last Updated : 11 Mar, 2025

Given string str. The task is to find the maximum occurring character in the string str.

Examples:

Input: geeksforgeeks
Output: e
Explanation: ‘e’ occurs 4 times in the string

Input: test
Output: t
Explanation: ‘t’ occurs 2 times in the string

Return the maximum occurring character in an input string using Hashing:

Naive approach : ( using unordered_map )

In this approach we simply use the unordered_map from STL to store the frequency of every character and while adding characters to map we take a variable count to determine the element having highest frequency.

Implementation :

C++

// C++ program for the above approach  #include <bits/stdc++.h>  using namespace std;  // function that return maximum occurring character char getMaxOccurringChar(string str) {        // create unordered_map to store frequency of every character     unordered_map<char,int>mp;          // to store length of string     int n = str.length();          // to store answer      char ans;          // to check count of answer character is less or greater     // than another elements count     int cnt=0;          // traverse the string      for(int i=0 ;i<n ; i++){         // push element into map and increase its frequency          mp[str[i]]++;                  // update answer and count         if(cnt < mp[str[i]]){             ans = str[i];             cnt = mp[str[i]];         }     }          return ans;      }  // Driver Code int main() {     string str = "sample string";     cout << "Max occurring character is: "          << getMaxOccurringChar(str); }  // this code is contributed by bhardwajji

#include <stdio.h> #include <stdlib.h> #include <string.h>  // Function to find the maximum occurring character char getMaxOccurringChar(char str[]) {     // Create a hash table (unordered_map) to store the     // frequency of each character     int count[256] = { 0 };      // Traverse the string and update the frequency of each     // character     int length = strlen(str);     for (int i = 0; i < length; i++)         count[(int)str[i]]++;      // Find the character with the maximum frequency     char maxChar;     int maxCount = 0;     for (int i = 0; i < length; i++) {         if (count[(int)str[i]] > maxCount) {             maxCount = count[(int)str[i]];             maxChar = str[i];         }     }      return maxChar; }  // Driver Code int main() {     char str[] = "sample string";     printf("Max occurring character is: %c\n",            getMaxOccurringChar(str));     return 0; }

Java

import java.util.*;  public class Main {          // function that returns maximum occurring character     static char getMaxOccurringChar(String str) {                  // create HashMap to store frequency of every character         HashMap<Character, Integer> mp = new HashMap<>();                  // to store length of string         int n = str.length();                  // to store answer          char ans = 0;                  // to check count of answer character is less or greater         // than another elements count         int cnt = 0;                  // traverse the string          for(int i = 0; i < n; i++) {                          // push element into map and increase its frequency              char c = str.charAt(i);             mp.put(c, mp.getOrDefault(c, 0) + 1);                          // update answer and count             if(cnt < mp.get(c)) {                 ans = c;                 cnt = mp.get(c);             }         }                  return ans;     }      // Driver Code     public static void main(String[] args) {         String str = "sample string";         System.out.println("Max occurring character is: " + getMaxOccurringChar(str));     } }  // This code is contributed by kalyanbef

Python

# function that return maximum occurring character def getMaxOccurringChar(str):     # create dictionary to store frequency of every character     mp = {}      # to store length of string     n = len(str)      # to store answer     ans = ''      # to check count of answer character is less or greater     # than another elements count     cnt = 0      # traverse the string     for i in range(n):         # push element into dictionary and increase its frequency         if str[i] in mp:             mp[str[i]] += 1         else:             mp[str[i]] = 1          # update answer and count         if cnt < mp[str[i]]:             ans = str[i]             cnt = mp[str[i]]      return ans   # Driver Code str = "sample string" print("Max occurring character is:", getMaxOccurringChar(str))

// C# program for the above approach using System; using System.Collections.Generic;  class MainClass {     public static void Main(string[] args)     {         string str = "sample string";         Console.WriteLine("Max occurring character is: "                           + getMaxOccurringChar(str));     }      // function that return maximum occurring character     static char getMaxOccurringChar(string str)     {         // create dictionary to store frequency of every         // character         Dictionary<char, int> mp             = new Dictionary<char, int>();          // to store length of string         int n = str.Length;          // to store answer         char ans = '\0';          // to check count of answer character is less or         // greater than another elements count         int cnt = 0;          // traverse the string         for (int i = 0; i < n; i++) {             // push element into map and increase its             // frequency             if (mp.ContainsKey(str[i])) {                 mp[str[i]]++;             }             else {                 mp.Add(str[i], 1);             }              // update answer and count             if (cnt < mp[str[i]]) {                 ans = str[i];                 cnt = mp[str[i]];             }         }          return ans;     } }

JavaScript

// JavaScript program for the above approach  // function that return maximum occurring character function getMaxOccurringChar(str) {      // create map to store frequency of every character     let mp = new Map();          // to store length of string     let n = str.length;          // to store answer      let ans;          // to check count of answer character is less or greater     // than another elements count     let cnt=0;          // traverse the string      for(let i=0 ;i<n ; i++){         // push element into map and increase its frequency          mp.set(str[i], (mp.get(str[i]) || 0) + 1);                  // update answer and count         if(cnt < mp.get(str[i])){             ans = str[i];             cnt = mp.get(str[i]);         }     }          return ans; }  // Driver Code let str = "sample string"; console.log("Max occurring character is: " + getMaxOccurringChar(str));  // This code is contributed by rutikbhosale

Output

Max occurring character is: s

Time Complexity: O(N), Traversing the string of length N one time.
Auxiliary Space: O(N), where N is the size of the string

The idea is to store the frequency of every character in the array and return the character with maximum count.

Follow the steps to solve the problem:

Create a count array of size 256 to store the frequency of every character of the string
Maintain a max variable to store the maximum frequency so far whenever encounter a frequency more than the max then update the max
And update that character in our result variable.

Below is the implementation of the above approach:

C++

#include <iostream> #include <unordered_map> #include <algorithm>  std::unordered_map<char, int> findMaxCharacterCount(const std::string& str) {     std::unordered_map<char, int> countMap;      // Count occurrences of each character     for (char ch : str) {         countMap[ch]++;     }      // Find the character with the maximum count     char maxChar = '\0';     int maxCount = 0;      for (const auto& entry : countMap) {         if (entry.second > maxCount) {             maxChar = entry.first;             maxCount = entry.second;         }     }      std::unordered_map<char, int> result;     result[maxChar] = maxCount;     return result; }  int main() {     std::string str = "geeksforgeeks";      // Call the function and print the result     std::unordered_map<char, int> result = findMaxCharacterCount(str);     std::cout << "Character: " << result.begin()->first << ", Count: " << result.begin()->second << std::endl;      return 0; }

Java

import java.util.HashMap; import java.util.Map;  public class Main {      public static Map<Character, Integer> findMaxCharacterCount(String str) {         // Initialize max with the first character and its count         Map<Character, Integer> max = new HashMap<>();         max.put(str.charAt(0), str.length() - str.replace(String.valueOf(str.charAt(0)), "").length());          // Iterate through the string to find the character with the maximum count         for (char i : str.toCharArray()) {             int count = str.length() - str.replace(String.valueOf(i), "").length();             if (count > max.get(max.keySet().iterator().next())) {                 // Update max if the count is higher                 max.clear();                 max.put(i, count);             }         }          return max;     }      public static void main(String[] args) {         String str = "geeksforgeeks";                  // Call the function and print the result         Map<Character, Integer> result = findMaxCharacterCount(str);         System.out.println("Character: " + result.keySet().iterator().next() + ", Count: " + result.get(result.keySet().iterator().next()));     } }

Python

from collections import defaultdict  def find_max_character_count(s):     count_map = defaultdict(int)      # Count occurrences of each character     for ch in s:         count_map[ch] += 1      # Find the character with the maximum count     max_char = ''     max_count = 0      for char, count in count_map.items():         if count > max_count:             max_char = char             max_count = count      return {max_char: max_count}  # Main function to test if __name__ == "__main__":     string = "geeksforgeeks"      # Call the function and print the result     result = find_max_character_count(string)     for char, count in result.items():         # Using .format() for string formatting compatibility with older Python versions         print("Character: {}, Count: {}".format(char, count))

using System; using System.Collections.Generic; using System.Linq;  class Program {     static Dictionary<char, int> FindMaxCharacterCount(string str)     {         Dictionary<char, int> countMap = new Dictionary<char, int>();          // Count occurrences of each character         foreach (char ch in str)         {             if (countMap.ContainsKey(ch))             {                 countMap[ch]++;             }             else             {                 countMap[ch] = 1;             }         }          // Find the character with the maximum count         char maxChar = '\0';         int maxCount = 0;          foreach (var entry in countMap)         {             if (entry.Value > maxCount)             {                 maxChar = entry.Key;                 maxCount = entry.Value;             }         }          Dictionary<char, int> result = new Dictionary<char, int>();         result[maxChar] = maxCount;         return result;     }      static void Main(string[] args)     {         string str = "geeksforgeeks";          // Call the function and print the result         Dictionary<char, int> result = FindMaxCharacterCount(str);         Console.WriteLine($"Character: {result.First().Key}, Count: {result.First().Value}");     } }

JavaScript

// Function to find the character with the maximum count in a string function findMaxCharacterCount(str) {     let countMap = {};      // Count occurrences of each character     for (let ch of str) {         if (countMap[ch])             countMap[ch]++;         else             countMap[ch] = 1;     }      // Find the character with the maximum count     let maxChar = '';     let maxCount = 0;      for (let [char, count] of Object.entries(countMap)) {         if (count > maxCount) {             maxChar = char;             maxCount = count;         }     }      let result = {};     result[maxChar] = maxCount;     return result; }  // Main function function main() {     let str = "geeksforgeeks";      // Call the function and print the result     let result = findMaxCharacterCount(str);     let maxEntry = Object.entries(result)[0];     console.log(`Character: ${maxEntry[0]}, Count: ${maxEntry[1]}`); }  // Invoke main function main();

Output

Character: e, Count: 4

Time Complexity: O(N), Traversing the string of length N one time.
Auxiliary Space: O(1)

Count Occurrences of a Given Character in a String

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Find maximum occurring character in a string

Return the maximum occurring character in an input string using Hashing:

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