## C++, sort, cocktail_selection_sort.cpp

``````// Returns Sorted elements after performing Cocktail Selection Sort
// It is a Sorting algorithm which chooses the minimum and maximum element in an
// array simultaneously, and swaps it with the lowest and highest available
// position iteratively or recursively

#include <algorithm>
#include <iostream>
#include <vector>

// Iterative Version

void CocktailSelectionSort(std::vector<int> *vec, int low, int high) {
while (low <= high) {
int minimum = (*vec)[low];
int minimumindex = low;
int maximum = (*vec)[high];
int maximumindex = high;

for (int i = low; i <= high; i++) {
if ((*vec)[i] >= maximum) {
maximum = (*vec)[i];
maximumindex = i;
}
if ((*vec)[i] <= minimum) {
minimum = (*vec)[i];
minimumindex = i;
}
}
if (low != maximumindex || high != minimumindex) {
std::swap((*vec)[low], (*vec)[minimumindex]);
std::swap((*vec)[high], (*vec)[maximumindex]);
} else {
std::swap((*vec)[low], (*vec)[high]);
}

low++;
high--;
}
}

// Recursive Version

void CocktailSelectionSort_v2(std::vector<int> *vec, int low, int high) {
if (low >= high)
return;

int minimum = (*vec)[low];
int minimumindex = low;
int maximum = (*vec)[high];
int maximumindex = high;

for (int i = low; i <= high; i++) {
if ((*vec)[i] >= maximum) {
maximum = (*vec)[i];
maximumindex = i;
}
if ((*vec)[i] <= minimum) {
minimum = (*vec)[i];
minimumindex = i;
}
}
if (low != maximumindex || high != minimumindex) {
std::swap((*vec)[low], (*vec)[minimumindex]);
std::swap((*vec)[high], (*vec)[maximumindex]);
} else {
std::swap((*vec)[low], (*vec)[high]);
}

CocktailSelectionSort(vec, low + 1, high - 1);
}

// main function, select any one of iterative or recursive version

int main() {
int n;
std::cout << "Enter number of elements\n";
std::cin >> n;
std::vector<int> v(n);
std::cout << "Enter all the elements\n";
for (int i = 0; i < n; ++i) {
std::cin >> v[i];
}

int method;
std::cout << "Enter method: \n\t0: iterative\n\t1: recursive:\t";
std::cin >> method;

if (method == 0) {
CocktailSelectionSort(&v, 0, n - 1);
} else if (method == 1) {
CocktailSelectionSort_v2(&v, 0, n - 1);
} else {
std::cerr << "Unknown method" << std::endl;
return -1;
}
std::cout << "Sorted elements are\n";
for (int i = 0; i < n; ++i) {
std::cout << v[i] << " ";
}

return 0;
}
``````