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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. 	interface NestedInteger {
  11. 		public Integer getInteger();
  12. 		public boolean isInteger();
  13. 		public List<NestedInteger> getList();
  14. 	}
  15.  
  16. 	static class NestedIntegerIterator {
  17. 		private final List<NestedInteger> list;
  18. 		private Integer nextInteger;
  19. 		private Stack<Iterator<NestedInteger>> stack;
  20.  
  21. 		public NestedIntegerIterator(List<NestedInteger> list) {
  22. 			this.list = list;
  23. 			stack = new Stack<Iterator<NestedInteger>>();
  24. 			stack.push(list.iterator());
  25. 			advance();
  26. 		}
  27.  
  28. 		public boolean hasNext() {
  29. 			return stack.empty() == false;
  30. 		}
  31.  
  32. 		public Integer next() {
  33. 			Integer next = this.nextInteger;
  34. 			advance();
  35. 			return next;
  36. 		}
  37.  
  38. 		private void advance() {
  39. 			while (stack.empty() == false) {
  40. 				Iterator<NestedInteger> it = stack.peek();
  41. 				if (it.hasNext() == false) {
  42. 					stack.pop();
  43. 				} else {
  44. 					NestedInteger ni = it.next();
  45. 					if (ni.isInteger()) {
  46. 						this.nextInteger = ni.getInteger();
  47. 						break;
  48. 					} else {
  49. 						stack.push(ni.getList().iterator());
  50. 					}
  51. 				}
  52. 			}
  53. 		}
  54. 	}
  55.  
  56. 	static class NestedIntegerImpl implements NestedInteger {
  57. 		private final Integer val;
  58.  
  59. 		public NestedIntegerImpl(int val) {
  60. 			this.val = val;
  61. 		}
  62.  
  63. 		public Integer getInteger() {
  64. 			return this.val;
  65. 		}
  66.  
  67. 		public boolean isInteger() {
  68. 			return true;
  69. 		}
  70.  
  71. 		public List<NestedInteger> getList() {
  72. 			return null;
  73. 		}
  74. 	}
  75.  
  76. 	static class NestedIntegerListImpl implements NestedInteger {
  77. 		private List<NestedInteger> list;
  78.  
  79. 		public NestedIntegerListImpl(List<NestedInteger> list) {
  80. 			this.list = new ArrayList<NestedInteger>();
  81. 			for (NestedInteger ni : list) {
  82. 				this.list.add(ni);
  83. 			}
  84. 		}
  85.  
  86. 		public Integer getInteger() {
  87. 			return null;
  88. 		}
  89.  
  90. 		public boolean isInteger() {
  91. 			return false;
  92. 		}
  93.  
  94. 		public List<NestedInteger> getList() {
  95. 			return list;
  96. 		}
  97. 	}
  98.  
  99. 	public static void main (String[] args) throws java.lang.Exception
  100. 	{
  101. 		// {0,{1,2}, 3 ,{4,{5, 6}}}
  102. 		List<NestedInteger> l1 = new ArrayList<NestedInteger>();
  103. 		List<NestedInteger> l2 = new ArrayList<NestedInteger>();
  104. 		List<NestedInteger> l3 = new ArrayList<NestedInteger>();
  105. 		List<NestedInteger> l4 = new ArrayList<NestedInteger>();
  106.  
  107. 		l4.add(new NestedIntegerImpl(5));
  108. 		l4.add(new NestedIntegerImpl(6));
  109.  
  110. 		l3.add(new NestedIntegerImpl(4));
  111. 		l3.add(new NestedIntegerListImpl(l4));
  112.  
  113. 		l2.add(new NestedIntegerImpl(1));
  114. 		l2.add(new NestedIntegerImpl(2));
  115.  
  116. 		l1.add(new NestedIntegerImpl(0));
  117. 		l1.add(new NestedIntegerListImpl(l2));
  118. 		l1.add(new NestedIntegerImpl(3));
  119. 		l1.add(new NestedIntegerListImpl(l3));
  120.  
  121. 		NestedIntegerIterator it1 = new NestedIntegerIterator(l1);
  122. 		while(it1.hasNext()) {
  123. 			System.out.println(it1.next());
  124. 		}
  125.  
  126. 		NestedIntegerIterator it2 = new NestedIntegerIterator(l2);
  127. 		while(it2.hasNext()) {
  128. 			System.out.println(it2.next());
  129. 		}
  130. 	}
  131. }
Success #stdin #stdout 0.1s 320320KB
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https://ideone.com/CIl8uy
Nested Integer Iterator
language:
Java (HotSpot 12)
created:
9 years ago
visibility:
secret

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