Modify String by Replacing Characters by Alphabets whose distance from that Character is Equal to its Frequency

Modifying a string by replacing characters with alphabets whose distance from that character is equal to its frequency is an intriguing problem that involves manipulating strings in a unique way. The task is to take a given string as input and replace each character in the string with an alphabet that is at a distance equal to the frequency of that character in the string. For instance, if the character 'a' appears three times in the string, it would be replaced by an alphabet that is three positions away from 'a' in the English alphabet. This problem presents an interesting challenge in terms of string manipulation and character encoding.

In this tutorial, we will explore how to solve this problem using C++ programming language. We will discuss the approach, logic, and implementation details to achieve this string modification and provide a step-by-step guide for readers to understand and implement the solution effectively. So, let's get started!

Problem Statement

Given a string as input, the task is to modify the string by replacing each character with an alphabet that is at a distance equal to the frequency of that character in the string.

Sample Examples

Example 1

Input: "hello"
Output: "ifmmp"


Explanation: In the input string "hello", the character 'h' appears once, 'e' appears once, and 'l' appears twice, while 'o' appears once. So, the modified string will have 'h' replaced with the alphabet that is one position away ('i' in this case), 'e' replaced with the alphabet that is one position away ('f' in this case), 'l' replaced with the alphabet that is two positions away ('n' in this case), and 'o' replaced with the alphabet that is one position away ('p' in this case).

Example 2

Input: "world"
Output: "wqtnf"


Explanation: In the input string "world", the character 'w' appears once, 'o' appears once, 'r' appears once, and 'l' appears once, while 'd' appears once. So, the modified string will have 'w' replaced with the alphabet that is one position away ('q' in this case), 'o' replaced with the alphabet that is one position away ('q' in this case), 'r' replaced with the alphabet that is one position away ('s' in this case), 'l' replaced with the alphabet that is one position away ('m' in this case), and 'd' replaced with the alphabet that is one position away ('e' in this case).

Note: The distance is calculated based on the English alphabet sequence, where 'a' is at a distance of 1 from 'b', 2 from 'c', and so on. The alphabet sequence is circular, so 'z' is at a distance of 1 from 'a'.

Algorithm

STEP 1: Read the input string from the user.

STEP 2: Create a frequency map to store the frequency of each character in the input string.

STEP 3: Loop through each character in the input string.

STEP 4: For each character, calculate its distance from 'a' in the English alphabet using ASCII value manipulation.

STEP 5: Replace the character with the alphabet that is at a distance equal to its frequency in the input string, taking care of circular wrapping.

STEP 6: Append the modified character to the output string.

STEP 7: Repeat steps 4-6 for all characters in the input string.

STEP 8: Print the modified string as the output.

So, now after understanding the above algorithm itβs time to implement this algorithm using C++. We are going to do this with the help of an example where we understand the implementation of this algorithm using C++ programming language.

Example

Implementation of the above algorithm using C++

The program uses a frequency map to store the frequency of each character in the input string. It then loops through each character in the input string and calculates its distance from 'a' in the English alphabet using ASCII value manipulation. The program replaces the character with the alphabet that is at a distance equal to its frequency in the input string, taking care of circular wrapping. The modified characters are stored in an output string, which is then displayed as the program's output. The program demonstrates the solution to the problem of modifying a string by replacing characters with alphabets whose distance from that character is equal to its frequency.

#include <iostream>
#include <string>
#include <unordered_map>
using namespace std;
// Function to modify string by replacing characters with alphabets whose distance from the character is equal to its frequency
string modifyString(string input) {
unordered_map<char, int> freqMap; // Frequency map to store character frequencies
// Calculate character frequencies
for (char ch : input) {
freqMap[ch]++;
}
string output = ""; // Output string to store modified characters
// Loop through each character in the input string
for (char ch : input) {
int freq = freqMap[ch]; // Frequency of current character
int distance = (ch - 'a' + freq) % 26; // Calculate distance from 'a' in the English alphabet
char modifiedChar = 'a' + distance; // Calculate modified character
output += modifiedChar; // Append modified character to output string
}
return output;
}
int main() {
// Test Example 1
string input1 = "hello";
string output1 = modifyString(input1);
cout << "Input: " << input1 << endl;
cout << "Output: " << output1 << endl;
// Test Example 2
string input2 = "world";
string output2 = modifyString(input2);
cout << "Input: " << input2 << endl;
cout << "Output: " << output2 << endl;
return 0;
}


Output

Input: hello
Output: ifnnp
Input: world
Output: xpsme


Conclusion

To conclude, we have discussed the problem of modifying a string by replacing characters with alphabets whose distance from that character is equal to its frequency. We have presented an algorithm that uses a frequency map and ASCII value manipulation to achieve the desired result. We have also provided a working C++ program that implements the algorithm and demonstrated its usage with two test examples. This problem is a good exercise for practising string manipulation, and the presented solution can be used as a reference for similar problems as well. Hope this tutorial helps!

Updated on: 08-Sep-2023

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