Maximum repeating character for every index in given String

Last Updated : 18 Jun, 2021

Given string str consisting of lowercase alphabets, the task is to find the maximum repeating character obtained for every character of the string. If for any index, more than one character has occurred a maximum number of times, then print the character which had occurred most recently.

Examples:

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Input: str = “abbc”
Output:
a -> 1
b -> 1
b -> 2
b -> 2
Explanation:
str[0] = ‘a’. Therefore, print a -> 1.
str[1] = ‘b’. Now ‘a’ and ‘b’ have equal frequency. Since, ‘b’ is the most recently occurring character, print b -> 1.
str[2] = ‘b’. Since ‘b’is the most repeating character, print b -> 2.
str[3] = ‘c’. Since ‘b’is the most repeating character, print b -> 2.

Input: str = “htdddg”
Output:h -> 1
t -> 1
d -> 1
d -> 2
d -> 3
d -> 3

Approach: Follow the steps given below to solve the problem:

Initialize an array, say freq[] to store the frequency of each distinct character in the string.
Initialize two variables, say max, charMax to store the frequency of maximum repeating character and the maximum repeating character respectively.
Traverse the string and update the frequency of current character, update the value of max and charMax.
Finally, print the value of charMax and max after every character traversal.

Below is the implementation of the above approach:

C++

// C++ Program to implement
// the above approach
#include <bits/stdc++.h>
using namespace std;
  
// Function to print the
// maximum repeating
// character at each index
// of the String
void findFreq(string str,
              int N)
{
  // Stores frequency of
  // each distinct character
  int freq[256];
   
  memset(freq, 0,
         sizeof(freq));
 
  // Stores frequency of
  // maximum repeating
  // character
  int max = 0;
 
  // Stores the character having
  // maximum frequency
  char charMax = '0';
 
  // Traverse the String
  for (int i = 0; i < N; i++)
  {
    // Stores current character
    char ch = str[i];
 
    // Update the frequency of str[i]
    freq[ch]++;
 
    // If frequency of current
    // character exceeds max
    if (freq[ch] >= max)
    {
      // Update max
      max = freq[ch];
 
      // Update charMax
      charMax = ch;
    }
 
    // Print the required output
    cout<< charMax << "->" <<
           max << endl;
  }
}
 
// Driver Code
int main()
{
  string str = "abbc";
 
  // Stores length of str
  int N = str.size();
 
  findFreq(str, N);
}
 
// This code is contributed by Rajput-Ji

Java

// Java program to implement
// the above approach
 
import java.util.*;
 
public class GFG {
 
    // Function to print the maximum repeating
    // character at each index of the string
    public static void findFreq(String str,
                                int N)
    {
 
        // Stores frequency of
        // each distinct character
        int[] freq = new int[256];
 
        // Stores frequency of maximum
        // repeating character
        int max = 0;
 
        // Stores the character having
        // maximum frequency
        char charMax = '0';
 
        // Traverse the string
        for (int i = 0; i < N; i++) {
 
            // Stores current character
            char ch = str.charAt(i);
 
            // Update the frequency of str[i]
            freq[ch]++;
 
            // If frequency of current
            // character exceeds max
            if (freq[ch] >= max) {
 
                // Update max
                max = freq[ch];
 
                // Update charMax
                charMax = ch;
            }
 
            // Print the required output
            System.out.println(
                charMax + " -> " + max);
        }
    }
 
    // Driver Code
    public static void main(String[] args)
    {
        String str = "abbc";
 
        // Stores length of str
        int N = str.length();
 
        findFreq(str, N);
    }
}

Python3

# Python3 program to implement
# the above approach
 
# Function to print the maximum repeating
# character at each index of the string
def findFreq(strr, N):
     
    # Stores frequency of
    # each distinct character
    freq = [0] * 256
 
    # Stores frequency of maximum
    # repeating character
    max = 0
 
    # Stores the character having
    # maximum frequency
    charMax = '0'
 
    # Traverse the string
    for i in range(N):
         
        # Stores current character
        ch = ord(strr[i])
 
        # Update the frequency of strr[i]
        freq[ch] += 1
 
        # If frequency of current
        # character exceeds max
        if (freq[ch] >= max):
 
            # Update max
            max = freq[ch]
 
            # Update charMax
            charMax = ch
 
        # Print the required output
        print(chr(charMax), "->", max)
 
# Driver Code
if __name__ == '__main__':
     
    strr = "abbc"
 
    # Stores length of strr
    N = len(strr)
 
    findFreq(strr, N)
 
# This code is contributed by mohit kumar 29

C#

// C# program to implement
// the above approach
using System;
class GFG{
 
// Function to print the maximum repeating
// character at each index of the string
public static void findFreq(String str,
                            int N)
{
  // Stores frequency of
  // each distinct character
  int[] freq = new int[256];
 
  // Stores frequency of maximum
  // repeating character
  int max = 0;
 
  // Stores the character having
  // maximum frequency
  char charMax = '0';
 
  // Traverse the string
  for (int i = 0; i < N; i++)
  {
    // Stores current character
    char ch = str[i];
 
    // Update the frequency of
    // str[i]
    freq[ch]++;
 
    // If frequency of current
    // character exceeds max
    if (freq[ch] >= max)
    {
      // Update max
      max = freq[ch];
 
      // Update charMax
      charMax = ch;
    }
 
    // Print the required output
    Console.WriteLine(charMax +
                      " -> " + max);
  }
}
 
// Driver Code
public static void Main(String[] args)
{
  String str = "abbc";
 
  // Stores length of str
  int N = str.Length;
 
  findFreq(str, N);
}
}
 
// This code is contributed by shikhasingrajput

Javascript

<script>
 
// JavaScript Program to implement
// the above approach
 
// Function to print the
// maximum repeating
// character at each index
// of the String
function findFreq(str, N) {
    // Stores frequency of
    // each distinct character
    let freq = new Array(256).fill(0);
 
 
    // Stores frequency of
    // maximum repeating
    // character
    let max = 0;
 
    // Stores the character having
    // maximum frequency
    let charMax = '0';
 
    // Traverse the String
    for (let i = 0; i < N; i++) {
        // Stores current character
        let ch = str[i].charCodeAt(0);
 
        // Update the frequency of str[i]
        freq[ch]++;
 
        // If frequency of current
        // character exceeds max
        if (freq[ch] >= max) {
            // Update max
            max = freq[ch];
 
            // Update charMax
            charMax = ch;
        }
 
        // Print the required output
        document.write(String.fromCharCode(charMax) + "->" +
        max + "<br>");
    }
}
 
// Driver Code
 
let str = "abbc";
 
// Stores length of str
let N = str.length;
 
findFreq(str, N);
 
 
// This code is contributed by gfgking
 
</script>

Output:

a -> 1
b -> 1
b -> 2
b -> 2

Time Complexity: O(N)
Auxiliary Space: O(1)

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