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  1. import java.util.*;
  2. import java.io.*;
  3.  
  4. class DequeException extends Exception {}
  5.  
  6. class Node <T>
  7. {
  8. 	T val;
  9. 	Node prev, next;
  10.  
  11. 	Node(T v, Node p, Node n) {val = v; prev = p; next = n;}
  12. }
  13.  
  14. class MyDeque <T>
  15. {
  16. 	int size;
  17. 	Node<T> first, last;
  18.  
  19. 	MyDeque() {
  20. 		size = 0;
  21. 		first = null;
  22. 		last = null;
  23. 	}
  24.  
  25. 	String pushBack(T val) {
  26. 		if (size > 0) {
  27. 			Node currentNode = new Node<T> (val, last, null);
  28. 			last.next = currentNode;
  29. 			last = currentNode;
  30. 			size++;
  31. 		}
  32. 		else {
  33. 			Node currentNode = new Node<T> (val, null, null);
  34. 			last = currentNode;
  35. 			first = currentNode;
  36. 			size++;
  37. 		}
  38. 		return "ok";
  39. 	}
  40.  
  41. 	String pushFront(T val) {
  42. 		if (size > 0) {
  43. 			Node currentNode = new Node<T> (val, null, first);
  44. 			first.prev = currentNode;
  45. 			first = currentNode;
  46. 			size++;
  47. 		}
  48. 		else {
  49. 			Node currentNode = new Node<T> (val, null, null);
  50. 			last = currentNode;
  51. 			first = currentNode;
  52. 			size++;
  53. 		}
  54. 		return "ok";
  55. 	}
  56.  
  57. 	T popFront() throws DequeException {
  58. 		if(size == 0) throw new DequeException();
  59. 		T v = first.val;
  60. 		first = first.next;
  61. 		size--;
  62. 		return v;
  63. 	}
  64.  
  65. 	T popBack() throws DequeException {
  66. 		if(size == 0) throw new DequeException();
  67. 		T v = last.val;
  68. 		last = last.prev;
  69. 		size--;
  70. 		return v;
  71. 	}
  72.  
  73. 	T front() throws DequeException {
  74. 		if(size == 0) throw new DequeException();
  75. 		return first.val;
  76. 	}
  77.  
  78. 	T back() throws DequeException {
  79. 		if(size == 0) throw new DequeException();
  80. 		return last.val;
  81. 	}
  82.  
  83. 	int getSize() {
  84. 		return size;
  85. 	}
  86.  
  87. 	String clear() {
  88. 		size = 0;
  89. 		return "ok";
  90. 	}
  91.  
  92. 	String ex() {
  93. 		return "bye";
  94. 	}
  95. }
  96.  
  97. class Main
  98. {
  99. 	public static void main (String[] args) {
  100. 		Scanner in = new Scanner(System.in);
  101. 		PrintWriter out = new PrintWriter(System.out);
  102. 		MyDeque<String> deque = new MyDeque<String>();
  103. 		String s, val;
  104.  
  105. 		while(in.hasNext()) {
  106. 			s = in.next();
  107. 			if (s.equals("exit")) out.println(deque.ex());
  108. 			else if (s.equals("clear")) out.println(deque.clear());
  109. 			else if (s.equals("size")) out.println(deque.getSize());
  110. 			else if (s.equals("back")) {
  111. 				try {
  112. 					out.println(deque.back());
  113. 				} catch(DequeException e) {
  114. 					out.println("error");
  115. 				}
  116. 			}
  117. 			else if(s.equals("front")) {
  118. 				try {
  119. 					out.println(deque.front());
  120. 				} catch(DequeException e) {
  121. 					out.println("error");
  122. 				}
  123. 			}
  124. 			else if (s.equals("pop_back")) {
  125. 				try {
  126. 					out.println(deque.popBack());
  127. 				} catch(DequeException e) {
  128. 					out.println("error");
  129. 				}
  130. 			}
  131. 			else if (s.equals("pop_front")) {
  132. 				try {
  133. 					out.println(deque.popFront());
  134. 				} catch(DequeException e) {
  135. 					out.println("error");
  136. 				}
  137. 			}
  138. 			else if(s.equals("push_back")) {
  139. 				val = in.next();
  140. 				out.println(deque.pushBack(val));
  141. 			}
  142. 			else if(s.equals("push_front")) {
  143. 				val = in.next();
  144. 				out.println(deque.pushFront(val));
  145. 			}
  146. 			out.flush();	
  147. 		}
  148. 	}
  149. }
Success #stdin #stdout 0.13s 29496KB
comments (?)
stdin
copy 
push_back 1
push_front 2
back
front
size
clear
size
pop_back
exit
stdout
copy 
ok
ok
1
2
2
ok
0
error
bye
https://ideone.com/LfoKO3
6129
language:
Java (HotSpot 12)
created:
7 years ago
visibility:
secret

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