Added C++ exercise folder

Some small C++ problems

cpp-exercises/BinarySearchTree.cpp

@@ -0,0 +1,67 @@
+#include <stdexcept>
+#include <string>
+#include <iostream>
+
+class Node
+{
+public:
+    Node(int value, Node* left, Node* right)
+    {
+        this->value = value;
+        this->left = left;
+        this->right = right;
+    }
+
+    int getValue() const
+    {
+        return value;
+    }
+
+    Node* getLeft() const
+    {
+        return left;
+    }
+
+    Node* getRight() const
+    {
+        return right;
+    }
+
+private:
+    int value;
+    Node* left;
+    Node* right;
+};
+
+class BinarySearchTree
+{
+public:
+    static bool contains(const Node& root, int value)
+    {
+        int node_value = root.getValue();
+        if (value == node_value){
+            return true;
+        }
+        else if (value > node_value && root.getRight() != NULL){
+
+            return contains(*root.getRight(), value);
+        }
+        else if (value < node_value && root.getLeft() != NULL){
+            return contains(*root.getLeft(), value);
+        }
+        else{
+            return false;
+        }
+    }
+};
+
+#ifndef RunTests
+int main()
+{
+    Node n1(1, NULL, NULL);
+    Node n3(3, NULL, NULL);
+    Node n2(2, &n1, &n3);
+
+    std::cout << BinarySearchTree::contains(n2, 3);
+}
+#endif

cpp-exercises/QuadraticEquation.cpp

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+#include <tuple>
+#include <stdexcept>
+#include <iostream>
+#include <string>
+#include <cmath>
+
+std::pair<double, double> findRoots(double a, double b, double c)
+{
+    double discriminant = std::pow(b,2) - 4*a*c;
+
+    std::pair<double, double> roots;
+
+    roots.first = (-b + std::sqrt(discriminant))/(2*a);
+    roots.second = (-b - std::sqrt(discriminant))/(2*a);
+
+    return roots;
+
+
+}
+
+#ifndef RunTests
+int main()
+{
+    std::pair<double,double> roots = findRoots(2, 10, 8);
+    std::cout << "Roots: " + std::to_string(roots.first) + ", " + std::to_string(roots.second);
+}
+#endif

cpp-exercises/train_composition_deque.cpp

@@ -0,0 +1,48 @@
+#include <stdexcept>
+#include <iostream>
+#include <deque>
+#include <chrono>
+
+class TrainComposition
+{
+private:
+    std::deque <int> train;
+
+public:
+    void attachWagonFromLeft(int wagonId)
+    {
+        this->train.push_back(wagonId);
+    }
+
+    void attachWagonFromRight(int wagonId)
+    {
+        this->train.push_front(wagonId);
+    }
+
+    int detachWagonFromLeft()
+    {
+        int wagonID = this->train.back();
+        this->train.pop_back();
+
+        return wagonID;
+    }
+
+    int detachWagonFromRight()
+    {
+        int wagonID = this->train.front();
+        this->train.pop_front();
+
+        return wagonID;
+    }
+};
+
+#ifndef RunTests
+int main()
+{
+    TrainComposition train;
+    train.attachWagonFromLeft(7);
+    train.attachWagonFromLeft(13);
+    std::cout << train.detachWagonFromRight() << "\n"; // 7 
+    std::cout << train.detachWagonFromLeft(); // 13
+}
+#endif