C++ Counting sort algorithm Exercise: Sort an array of elements using the Counting sort algorithm

Last update on December 20 2024 12:31:48 (UTC/GMT +8 hours)

Write a C++ program to sort an array of elements using the Counting sort algorithm.

Sample Solution:

C++ Code :

// Including necessary C++ libraries
#include <algorithm>
#include <iterator>
#include <iostream>
#include <vector>

// Function to perform counting sort algorithm
template<typename ForwardIterator>
void counting_sort(ForwardIterator begin, ForwardIterator end) {
  // Finding the minimum and maximum elements in the range
  auto min_max = std::minmax_element(begin, end);

  // If the range is empty, return as there's no sorting needed
  if (min_max.first == min_max.second) {
    return;
  }

  // Determining the minimum and maximum values
  auto min = *min_max.first;
  auto max = *min_max.second;

  // Creating a count vector to store the frequency of elements
  std::vector<unsigned> count((max - min) + 1, 0u);

  // Counting the occurrences of each element in the range
  for (auto i = begin; i != end; ++i) {
    ++count[*i - min];
  }

  // Reconstructing the sorted sequence using count information
  for (auto i = min; i <= max; ++i) {
    for (auto j = 0; j < count[i - min]; ++j) {
      *begin++ = i;
    }
  }
}

// Main function
int main() {
  // Initializing an array of integers for sorting
  int a[] = {125, 0, 695, 3, -256, -5, 214, 44, 55};

  // Displaying the original numbers in the array
  std::cout << "Original numbers:\n";
  std::copy(std::begin(a), std::end(a), std::ostream_iterator<int>(std::cout, " "));
  std::cout << "\n";

  // Sorting the array using counting_sort function
  counting_sort(std::begin(a), std::end(a));

  // Displaying the sorted numbers after counting sort
  std::cout << "Sorted numbers:\n";
  std::copy(std::begin(a), std::end(a), std::ostream_iterator<int>(std::cout, " "));
  std::cout << "\n";

  // Returning 0 to indicate successful execution
  return 0;
}

Sample Output:

Original numbers:
125 0 695 3 -256 -5 214 44 55 
Sorted numbers:
-256 -5 0 3 44 55 125 214 695

Flowchart:

C++ Code Editor:

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