#include <stdexcept>
#include <iostream>
struct Tree
{
Tree* root;
Tree* left;
Tree* right;
int value;
};
class TrainComposition
{
private:
Tree* tree;
public:
TrainComposition()
{
tree = new Tree();
tree->root = nullptr;
tree->left = nullptr;
tree->right = nullptr;
tree->value = 0;
}
~TrainComposition()
{
delete tree;
}
void attachWagonFromLeft(int wagonId)
{
auto *temp = new Tree();
temp->root = &findLastLeft(*tree);
temp->value = wagonId;
temp->root->left = temp;
temp->left = nullptr;
temp->right = nullptr;
}
void attachWagonFromRight(int wagonId)
{
auto *temp = new Tree();
temp->root = &findLastRight(*tree);
temp->value = wagonId;
temp->root->right = temp;
temp->left = nullptr;
temp->right = nullptr;
}
int detachWagonFromLeft()
{
auto temp = findLastLeft(*tree);
if (temp.root == nullptr && temp.root->right != nullptr)
return temp.root->right->value;
temp.root->left = nullptr;
return temp.value;
}
int detachWagonFromRight()
{
auto temp = findLastRight(*tree);
if (temp.root == nullptr && temp.root->left != nullptr)
return temp.root->left->value;
temp.root->right = nullptr;
return temp.value;
}
Tree& findLastLeft(Tree& t)
{
if (t.left == nullptr)
return t;
findLastLeft(*t.left);
}
Tree& findLastRight(Tree& t)
{
if (t.right == nullptr)
return t;
findLastRight(*t.right);
}
};
#ifndef RunTests
int main()
{
TrainComposition tree;
tree.attachWagonFromLeft(7);
tree.attachWagonFromLeft(13);
tree.attachWagonFromRight(8);
std::cout << tree.detachWagonFromRight() << "\n"; // 7
std::cout << tree.detachWagonFromLeft(); // 13
return EXIT_SUCCESS;
}
#endif
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