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  1. #include <cstddef>
  2. #include <iostream>
  3. #include <string>
  4.  
  5. // ------ Grocery.hpp ------
  6.  
  7. struct Grocery
  8. {
  9. 	std::string name;
  10. 	std::size_t quantity;
  11. 	Grocery* next;
  12.  
  13. 	Grocery(std::string name, std::size_t quantity)
  14. 		: name(name)
  15. 		, quantity(quantity)
  16. 	{}
  17. };
  18.  
  19. namespace
  20. {
  21. 	std::ostream& operator<<(std::ostream& out, Grocery const& obj)
  22. 	{
  23. 		return out << obj.name << ", " << obj.quantity;
  24. 	}
  25. }
  26.  
  27. // ------ GroceryList.hpp ------
  28.  
  29. class LinkedGroceryList
  30. {
  31. private:
  32. 	Grocery* head;
  33. 	Grocery* tail;
  34. 	std::size_t numGroceries;
  35. 	std::size_t quantitySum;
  36.  
  37. public:
  38. 	LinkedGroceryList();
  39. 	~LinkedGroceryList();
  40. 	void addGrocery(Grocery const& grocery);
  41. 	void removeGrocery(Grocery const& grocery);
  42. 	std::size_t different() const { return numGroceries; }
  43. 	std::size_t total() const { return quantitySum; }
  44. 	bool empty() const { return quantitySum == 0; }
  45. 	friend std::ostream& operator<<(std::ostream& out, LinkedGroceryList const& obj);
  46. };
  47.  
  48. // ------ GroceryList.cpp ------
  49.  
  50. LinkedGroceryList::LinkedGroceryList()
  51. 	: head(nullptr)
  52. 	, tail(nullptr)
  53. 	, numGroceries(0)
  54. 	, quantitySum(0)
  55. {}
  56.  
  57. LinkedGroceryList::~LinkedGroceryList()
  58. {
  59. 	Grocery *predPtr = head;
  60. 	Grocery *nextGrocery;
  61.  
  62. 	while (predPtr)
  63. 	{
  64. 		nextGrocery = predPtr->next;
  65. 		delete predPtr;
  66. 		predPtr = nextGrocery;
  67. 	}
  68. }
  69.  
  70. void LinkedGroceryList::addGrocery(Grocery const& grocery)
  71. {
  72. 	Grocery* newGrocery = new Grocery(grocery.name, grocery.quantity);
  73. 	newGrocery->next = nullptr;
  74.  
  75. 	if (empty())
  76. 	{
  77. 		head = tail = newGrocery;
  78. 	}
  79. 	else
  80. 	{
  81. 		tail->next = newGrocery;
  82. 		tail = newGrocery;
  83. 	}
  84.  
  85. 	numGroceries++;
  86. 	quantitySum += grocery.quantity;
  87. }
  88.  
  89. void LinkedGroceryList::removeGrocery(Grocery const& grocery)
  90. {
  91. 	if (!head) return;
  92.  
  93. 	Grocery* groceryPtr;
  94.  
  95. 	if (head->name == grocery.name)
  96. 	{
  97. 		groceryPtr = head;
  98. 		head = groceryPtr->next;
  99.  
  100. 		quantitySum -= grocery.quantity;
  101. 		if (grocery.quantity == groceryPtr->quantity)
  102. 			numGroceries--;
  103. 		else
  104. 		{
  105. 			groceryPtr->quantity -= grocery.quantity;
  106. 			return;
  107. 		}
  108.  
  109. 		delete groceryPtr;
  110. 	}
  111. 	else
  112. 	{
  113. 		Grocery* predPtr = nullptr;
  114. 		groceryPtr = head;
  115.  
  116. 		while (groceryPtr && groceryPtr->name != grocery.name)
  117. 		{
  118. 			predPtr = groceryPtr;
  119. 			groceryPtr = groceryPtr->next;
  120. 		}
  121.  
  122. 		if (groceryPtr)
  123. 		{
  124. 			quantitySum -= grocery.quantity;
  125. 			if (grocery.quantity == groceryPtr->quantity)
  126. 				numGroceries--;
  127. 			else
  128. 			{
  129. 				groceryPtr->quantity -= grocery.quantity;
  130. 				return;
  131. 			}
  132.  
  133. 			predPtr->next = groceryPtr->next;
  134. 			delete groceryPtr;
  135. 		}
  136. 	}
  137. }
  138.  
  139. std::ostream& operator<<(std::ostream& out, LinkedGroceryList const& obj)
  140. {
  141. 	for (Grocery* grocery = obj.head; grocery; grocery = grocery->next)
  142. 	{
  143. 		out << *grocery << "\n";
  144. 	}
  145.  
  146. 	return out;
  147. }
  148.  
  149. // ------ Driver ------
  150.  
  151. int main()
  152. {
  153. 	LinkedGroceryList meats;
  154. 	meats.addGrocery(Grocery("steak", 5));
  155. 	meats.addGrocery(Grocery("chicken", 3));
  156. 	meats.addGrocery(Grocery("pork", 2));
  157.  
  158. 	std::cout << meats;
  159. 	std::cout << "\nDifferent items: " << meats.different() << "\n";
  160. 	std::cout << "Total items: " << meats.total();
  161.  
  162. 	std::cout << "\n\nRemoving 1 pork...\n\n";
  163. 	meats.removeGrocery(Grocery("pork", 1));
  164.  
  165. 	std::cout << meats;
  166. 	std::cout << "\nDifferent items: " << meats.different() << "\n";
  167. 	std::cout << "Total items: " << meats.total();
  168. }
Success #stdin #stdout 0s 3432KB
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steak, 5
chicken, 3
pork, 2

Different items: 3
Total items: 10

Removing 1 pork...

steak, 5
chicken, 3
pork, 1

Different items: 3
Total items: 9
https://ideone.com/mKNkh7
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
secret

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