Remove consecutive characters from a string expression


Consecutive characters in a string can sometimes clutter our data and make it harder to process. Whether you are a programmer, a data analyst, or simply someone dealing with textual data, there may come a time when you need to remove consecutive characters from a string. In this article, we will explore the problem of removing consecutive characters, understand how it works, delve into the algorithm and solution, provide C++ code examples, and analyze the time and space complexity of the solution.

 

How Does It Work?

The task of removing consecutive characters from a string involves scanning the string and eliminating any characters that repeat consecutively. For instance, if we have the string "aaabbcdddeee," removing consecutive characters would result in "abcde."

 

Algorithm

We can solve this problem efficiently with a simple algorithm:

  1. Initialize an empty string to store the result.
  2. Iterate through the input string character by character.
  3. If the current character is equal to the previous character, skip it.
  4. If the current character is different from the previous character, append it to the result string.
  5. Continue this process until you have processed the entire input string.
  6. The result string will contain the input string with consecutive characters removed.

 

Complexity

The time complexity of this solution is O(n), where n is the length of the input string. We iterate through the string once, and each character is processed once.
The space complexity is O(n) as well. This is because we store the result string, which can be at most the same length as the input string if there are no consecutive characters.

 

C++ Code
#include <iostream>
#include <string>

// Function to remove consecutive characters from a string
std::string removeConsecutiveCharacters(const std::string& input) {
   // If the input string is empty, return it as is
   if (input.empty()) {
       return input;
   }

   // Initialize an empty string to store the result
   std::string result = "";

   // Initialize a variable to keep track of the previous character
   char prev_char = input[0];

   // Append the first character of the input to the result
   result += prev_char;

   // Iterate through the input string starting from the second character
   for (size_t i = 1; i < input.length(); ++i) {
       // If the current character is different from the previous character, append it to the result
       if (input[i] != prev_char) {
           result += input[i];
           // Update the previous character
           prev_char = input[i];
       }
   }

   // Return the result string with consecutive characters removed
   return result;
}

int main() {
   // Example input string
   std::string input_string = "aaabbcdddeee";

   // Call the removeConsecutiveCharacters function
   std::string result = removeConsecutiveCharacters(input_string);
   
   // Print the original and modified strings
   std::cout << "Original string: " << input_string << std::endl;
   std::cout << "String with consecutive characters removed: " << result << std::endl;

   return 0;
}

Output

Original string: aaabbcdddeee
String with consecutive characters removed: abcde



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