Implementing the sets without C++ STL containers
If you want to implement sets (collections of unique elements) without using C++ STL containers like std::set or std::unordered_set, you can create your own set data structure from scratch. Here, I’ll provide a simple example of how to implement a basic set using an array in C++. Keep in mind that this is a simplified implementation and doesn’t have the same level of functionality and performance as the STL containers.
#include <iostream>
class CustomSet {
private:
int* elements; // Dynamic array to store elements
int capacity; // Maximum capacity of the set
int size; // Current size of the set
public:
CustomSet(int capacity) {
this->capacity = capacity;
this->size = 0;
this->elements = new int[capacity];
}
~CustomSet() {
delete[] elements;
}
bool contains(int element) {
for (int i = 0; i < size; i++) {
if (elements[i] == element) {
return true;
}
}
return false;
}
bool insert(int element) {
if (contains(element)) {
return false; // Element already exists in the set
}
if (size >= capacity) {
// Resize the array (this is a simplified approach)
int newCapacity = capacity * 2;
int* newElements = new int[newCapacity];
for (int i = 0; i < size; i++) {
newElements[i] = elements[i];
}
delete[] elements;
elements = newElements;
capacity = newCapacity;
}
elements[size++] = element;
return true;
}
bool remove(int element) {
int index = -1;
for (int i = 0; i < size; i++) {
if (elements[i] == element) {
index = i;
break;
}
}
if (index == -1) {
return false; // Element not found in the set
}
// Replace the element to remove with the last element
elements[index] = elements[size - 1];
size--;
return true;
}
void print() {
std::cout << "CustomSet: ";
for (int i = 0; i < size; i++) {
std::cout << elements[i] << " ";
}
std::cout << std::endl;
}
};
int main() {
CustomSet set(5);
set.insert(3);
set.insert(1);
set.insert(5);
set.insert(3); // This won't be inserted again since it's a set
set.insert(2);
set.print(); // Print the set
set.remove(1);
set.remove(4); // Element not found, nothing happens
set.print(); // Print the modified set
return 0;
}In this code, we define a CustomSet class that uses a dynamic array to store elements. The contains, insert, and remove methods provide basic set operations. The insert method also resizes the array if the capacity is exceeded. This is a very simplified example, and a production-ready set implementation would need to handle more edge cases and provide better performance.