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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6.  
  7. /* Name of the class has to be "Main" only if the class is public. */
  8. class Ideone
  9. {
  10. 	public static void main (String[] args) throws java.lang.Exception
  11. 	{
  12. 		try { 
  13. 			// your code goes here
  14. 		SStack<String> stack = new SStack();
  15. 		boolean threwException;
  16. 		threwException = false;
  17. 		try {
  18. 			stack.peek();
  19. 		}
  20. 		catch(EmptyStackException e)
  21. 		{
  22. 			threwException = true;
  23. 		}
  24. 		finally
  25. 		{
  26. 			if(!threwException)
  27. 			{
  28. 				System.out.println("peek for empty is broken");
  29. 			}
  30. 		}
  31.  
  32. 		threwException = false;
  33. 		try {
  34. 			stack.pop();
  35. 		}
  36. 		catch(EmptyStackException e)
  37. 		{
  38. 			threwException = true;
  39. 		}
  40. 		finally
  41. 		{
  42. 			if(!threwException)
  43. 			{
  44. 				System.out.println("pop for empty is broken");
  45. 			}
  46. 		}
  47. 		String one = "1";
  48. 		String two = "2";
  49. 		String three = "3";
  50.  
  51. 		stack.push(one);
  52. 		assertTrue(stack.pop().equals(one));
  53.  
  54. 		threwException = false;
  55. 		try {
  56. 			stack.pop();
  57. 		}
  58. 		catch(EmptyStackException e)
  59. 		{
  60. 			threwException = true;
  61. 		}
  62. 		finally
  63. 		{
  64. 			if(!threwException)
  65. 			{
  66. 				System.out.println("pop does not remove objects");
  67. 			}
  68. 		}
  69.  
  70. 		stack.push(one);
  71. 		stack.push(one);
  72. 		assertTrue(stack.pop().equals(one));
  73. 		assertTrue(stack.pop().equals(one));//duplicate object test
  74.  
  75. 		stack.push(one);
  76. 		stack.push(two);
  77. 		stack.push(three);
  78.  
  79. 		assertTrue(stack.pop().equals(three), three);
  80. 		assertTrue(stack.pop().equals(two), two);
  81. 		assertTrue(stack.pop().equals(one), one);//in order test
  82.  
  83. 		stack.push(one);
  84. 		stack.push(two);
  85.  
  86. 		assertTrue(stack.pop().equals(two), two);
  87.  
  88. 		stack.push(three);
  89. 		assertTrue(stack.peek().equals(three), three); //peek test
  90. 		assertTrue(stack.pop().equals(three), three);
  91.  
  92. 		assertTrue(stack.pop().equals(one), one);//test for adding items after removing
  93. 		} catch(Exception e)
  94. 		{
  95. 			System.out.println(e.getMessage());
  96. 		}
  97. 	}
  98.  
  99. 	public static void assertTrue(boolean value){
  100. 		if(!value){
  101. 			throw new IllegalStateException("code is bork");
  102. 		}
  103. 	}
  104. 	public static void assertTrue(boolean value, String message){
  105. 		if(!value){
  106. 			throw new IllegalStateException("code is bork: "+message);
  107. 		}
  108. 	}
  109. }
  110.  
  111. class SStack<T> {
  112.  
  113.     private class Node {
  114.  
  115.         private T data;
  116.         private Node prev, next;
  117.  
  118.         public Node() {
  119.         }
  120.  
  121.         public Node(T data) {
  122.             this.data = data;
  123.         }
  124.     }
  125.  
  126.     private Node top;
  127.  
  128.     public SStack() {
  129.         top = null;
  130.     }
  131.  
  132.     public boolean empty() {
  133.         return top == null;
  134.     }
  135.  
  136.     public T peek() {
  137.         if (top == null) {
  138.             throw new EmptyStackException();
  139.         }
  140.         return top.data;
  141.     }
  142.  
  143.     public T pop() {
  144.         if (top == null) {
  145.             throw new EmptyStackException();
  146.         }
  147.         T value = top.data;
  148.         top = top.prev;
  149.         return value;
  150.     }
  151.  
  152.     public T push(T data) {
  153.         Node temp = new Node(data);
  154.         if (top == null) {
  155.             top = temp;
  156.         } else {
  157.             top.next = temp;
  158.             temp.prev = top;
  159.             top = temp;
  160.         }
  161.         return temp.data;
  162.     }
  163. }
Success #stdin #stdout 0.09s 320576KB
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https://ideone.com/BACWBr
language:
Java (HotSpot 12)
created:
8 years ago
visibility:
public

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