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  1. #include <iostream>
  2. #include <string>
  3. using namespace std;
  4.  
  5. class Deque{
  6. 	private:
  7. 	int *a = new int [100];
  8. 	int size_;
  9. 	int front_;
  10. 	int back_;
  11. 	int capacity;
  12. 	void resize(int);
  13. 	public:
  14. 	Deque(): size_(0), front_(1), back_(0), capacity(100){}
  15. 	void push_back(int);
  16. 	void push_front(int);
  17. 	void pop_back();
  18. 	void pop_front();
  19. 	int size() const;
  20. 	int back() const;
  21. 	int front() const;
  22. 	void clear();
  23. };
  24.  
  25. void Deque::resize(int newcapacity){
  26. 	int* tmp = new int [newcapacity];
  27. 	int j = front_;
  28. 	for(int i = 0; j!= back_; ++i){
  29. 		tmp[i] = a[j];
  30. 		j = (j+1)%capacity;
  31. 	}
  32. 	tmp[size_ - 1] = a[back_];
  33. 	delete []a;
  34. 	a = tmp;
  35. 	capacity = newcapacity;
  36. 	front_ = 0;
  37. 	back_ = size_ - 1;
  38. }
  39.  
  40. void Deque::push_back(int b){
  41. 	if(size_ == capacity){
  42. 		this -> resize(2*capacity);
  43. 	}
  44. 	back_ = (back_ + 1)%capacity;
  45. 	a[back_] = b;
  46. 	size_++;
  47. }
  48. void Deque::push_front(int b){
  49. 	if(size_ == capacity){
  50. 		this -> resize(2*capacity);
  51. 	}
  52. 	front_ = (front_ - 1 + capacity)%capacity;
  53. 	a[front_] = b;
  54. 	size_++;
  55. }
  56.  
  57. void Deque::pop_back(){
  58. 	back_ = (back_ - 1 + capacity)%capacity;
  59. 	size_--;
  60. }
  61. void Deque::pop_front(){
  62. 	front_ = (front_ + 1 + capacity)%capacity;
  63. 	size_--;
  64. }
  65. int Deque::size() const{
  66. 	return size_;
  67. }
  68.  
  69. int Deque::front() const{
  70. 	return a[front_];
  71. }
  72.  
  73. int Deque::back() const{
  74. 	return a[back_];
  75. }
  76.  
  77. void Deque::clear(){
  78. 	back_ = 0;
  79. 	front_ = 1;
  80. 	size_ = 0;
  81. }
  82.  
  83. int main() {
  84. 	Deque a;
  85. 	string s;
  86. 	int n;
  87. 	while(cin >> s){
  88. 		if(s == "push_back"){
  89. 			cin >> n;
  90. 			a.push_back(n);
  91. 			cout << "ok\n";
  92. 		}
  93. 		else if(s == "push_front"){
  94. 			cin >> n;
  95. 			a.push_front(n);
  96. 			cout << "ok\n";
  97. 		}
  98. 		else if(s == "pop_back"){
  99. 			if(a.size()){
  100. 				cout << a.back() << endl;
  101. 				a.pop_back();
  102. 			}
  103. 			else{
  104. 				cout << "error\n";
  105. 			}
  106. 		}
  107. 		else if(s == "pop_front"){
  108. 			if(a.size()){
  109. 				cout << a.front() << endl;
  110. 				a.pop_front();
  111. 			}
  112. 			else{
  113. 				cout << "error\n";
  114. 			}
  115. 		}
  116. 		else if(s == "front"){
  117. 			if(a.size()){
  118. 				cout << a.front() << endl;
  119. 			}
  120. 			else{
  121. 				cout << "error\n";
  122. 			}
  123. 		}
  124. 		else if(s == "back"){
  125. 			if(a.size()){
  126. 				cout << a.back() << endl;
  127. 			}
  128. 			else{
  129. 				cout << "error\n";
  130. 			}
  131. 		}
  132. 		else if(s == "size"){
  133. 			cout << a.size() << endl;
  134. 		}
  135. 		else if(s == "clear"){
  136. 			cout << "ok\n";
  137. 			a.clear();
  138. 		}
  139. 		else if(s == "exit"){
  140. 			cout << "bye\n";
  141. 			return 0;
  142. 		}
  143. 	}
  144. 	return 0;
  145. }
Success #stdin #stdout 0s 3236KB
comments (?)
stdin 
push_back 4
back
front
stdout 
ok
4
4
https://ideone.com/4LcZ1Q
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
secret

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