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  1. #include <iostream>
  2. #include <vector>
  3. #include <string>
  4. #include <sstream>
  5. using namespace std;
  6.  
  7. enum class ElemType
  8. {
  9. 	VAL, 
  10. 	DOWN, 
  11. 	UP, 
  12. 	NONE
  13. }; 
  14.  
  15. class Elem
  16. {
  17. 	public: 
  18. 	Elem(): t(ElemType::VAL), val(0) {}
  19. 	Elem(const ElemType _t, const int _val): t(_t), val(_val) {}
  20. 	Elem(const ElemType _t) : Elem(_t, 0) {}
  21.  
  22. 	ElemType t; 
  23. 	int val; 
  24. }; 
  25.  
  26.  
  27. class MyDS
  28. {
  29. 	public: 
  30. 	// Initialization Example: [[1,2],3,[4,5],[], [6]]
  31. 	MyDS(): v({{ElemType::DOWN}, {ElemType::VAL,1}, {ElemType::VAL,2}, {ElemType::UP}, {ElemType::VAL,3}, {ElemType::DOWN}, {ElemType::VAL,4}, {ElemType::VAL,5}, {ElemType::UP}, {ElemType::DOWN}, {ElemType::NONE}, {ElemType::UP}, {ElemType::DOWN}, {ElemType::VAL,6}, {ElemType::UP}}) {}
  32.  
  33. 	vector<Elem> v;
  34.  
  35. 	string toStr() const 
  36. 	{
  37. 		stringstream res; 
  38. 		unsigned int curr_depth=0; 
  39.  
  40. 		bool isComma=false; 
  41. 		for(const auto& e : v)
  42. 		{
  43. 			if(e.t == ElemType::DOWN) {res << (isComma?",":"") << "["; isComma=false;} 
  44. 			else if(e.t == ElemType::UP) {res << "]"; isComma=true; }
  45. 			else if(e.t == ElemType::VAL) {res << ( (isComma)?",":"" ) << e.val; isComma=true;} 
  46. 			else if(e.t == ElemType::NONE) {res << ""; isComma=true;} 
  47. 		}
  48.  
  49. 		return res.str(); 
  50. 	}
  51. }; 
  52.  
  53. template <typename T>
  54. class MaybeMonad
  55. {
  56. 	public: 
  57. 	MaybeMonad(const T& _data): isValid(true), data(_data) {}
  58. 	MaybeMonad() : isValid(false), data(0) {}
  59.  
  60. 	bool isValid; 
  61. 	T data; 
  62.  
  63. 	string toStr() const 
  64. 	{
  65. 		if(isValid) return to_string(data); 
  66. 		return ""; 
  67. 	}
  68. }; 
  69.  
  70. class Iterator
  71. {
  72. 	public: 
  73. 	Iterator(const MyDS& _d) : is_index_valid(false), index(0), d(_d),  n_vals(0), tot_n_vals(count()) {}
  74.  
  75.  
  76. 	bool hasNext() const
  77. 	{
  78. 		return n_vals<tot_n_vals; 
  79. 	}
  80.  
  81. 	MaybeMonad<int> get() 
  82. 	{
  83. 		//MaybeMonad<int> res; 
  84. 		if(!is_index_valid) {is_index_valid=true; index=0;}
  85. 		else index++; 
  86. 		if(index == d.v.size()) {throw runtime_error("No more elements"); }
  87.  
  88. 		while( (d.v[index].t != ElemType::VAL) && (d.v[index].t != ElemType::NONE) )
  89. 		{
  90. 			index++; 
  91. 			if(index == d.v.size()) {throw runtime_error("No more elements");}  
  92. 		}
  93.  
  94. 		n_vals++; 		
  95. 		if(d.v[index].t == ElemType::VAL) return MaybeMonad<int>(d.v[index].val); 
  96. 		index++; 
  97. 		return MaybeMonad<int>(); 
  98. 	}
  99.  
  100. 	private: 
  101.  
  102. 	// Just get the reference, do not copy it 
  103. 	const MyDS& d; 
  104.  
  105. 	bool is_index_valid; 
  106. 	unsigned int index; 
  107. 	unsigned int n_vals; 
  108. 	unsigned int tot_n_vals; 
  109.  
  110.  
  111. 	// O(N) loop to count the actual elements 
  112. 	unsigned int count() const 
  113. 	{
  114. 		unsigned int res=0; 
  115. 		for(const auto& e : d.v) res += ( (e.t == ElemType::VAL) || (e.t == ElemType::NONE) )?1:0; 
  116. 		return res; 
  117. 	}
  118. }; 
  119.  
  120. int main() {
  121. 	// your code goes here
  122. 	MyDS d; 
  123. 	cout << d.toStr() << endl; 
  124. 	Iterator it(d); 
  125. 	while(it.hasNext()) cout << it.get().toStr() << ","; 
  126. 	cout << endl; 
  127. 	return 0;
  128. }
  129.  
  130.  
  131.  
  132.  
  133.  
Success #stdin #stdout 0s 4280KB
comments (?)
stdin 
Standard input is empty
stdout 
[1,2],3,[4,5],[],[6]
1,2,3,4,5,,6,
https://ideone.com/hpDodg
language:
C++ (gcc 8.3)
created:
6 years ago
visibility:
secret

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