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;
}
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
# 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 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
OutputMax 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;
}
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()));
}
}
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}");
}
}
// 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();
OutputCharacter: e, Count: 4
Time Complexity: O(N), Traversing the string of length N one time.
Auxiliary Space: O(1)
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