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  1. // 若干修正
  2. #include <iostream>
  3. #include <sstream>
  4. #include <vector>
  5. #include <map>
  6. #include <algorithm>
  7. #include <functional>
  8.  
  9. using namespace std;
  10.  
  11. template <class N>
  12. struct calculator {
  13. 	typedef string op_type;
  14. 	typedef map<op_type, function<N(N,N)> > op_map;
  15.  
  16. 	vector<N>  elems;
  17. 	vector<op_type> ops;
  18.  
  19. 	op_map s_opmap = {
  20. 		{"+", plus<N>()},    {"-", minus<N>()},
  21. 		{"/", divides<N>()}, {"*", multiplies<N>()} };
  22.  
  23. 	vector<vector<op_type>> prio = { {"*","/"}, {"+","-"} };
  24.  
  25. 	calculator(vector<N>& e) : elems(e) {}
  26.  
  27. 	bool validate(){
  28. 		vector<N> cvals(elems);
  29. 		vector<op_type>  cops(ops);
  30.  
  31. 		for( auto ops: prio )
  32. 			for( int i = 0; i < cops.size(); i++ )
  33. 				if( any_of( ops.begin(), ops.end(),
  34. 						bind( equal_to<op_type>(), cops[i], placeholders::_1 ) )
  35. 				){
  36. 					cvals[i] = s_opmap[ cops[i] ](cvals[i],cvals[i+1]);
  37.  
  38. 					cvals.erase(cvals.begin() + i+1);
  39. 					cops.erase(cops.begin() + i--);
  40. 				}
  41.  
  42. 		return ( cvals.size() == 2 && cvals.back() == cvals.front() );
  43. 	}
  44.  
  45. 	void calculate(){
  46. 		this->ops = vector<op_type>();
  47. 		bool found = next_comb();
  48.  
  49. 		cout << elems[0] << " "; // head
  50. 		for( size_t i = 1; i < elems.size() -1; i++ )
  51. 			found && (cout << ops[i-1]), cout << " " << elems[i] << " ";
  52.  
  53. 		cout << (found ? "= " : "has no op-combs to be ") << elems.back() << endl;
  54. 	}
  55.  
  56. 	bool next_comb(){
  57. 		return ( ops.size() == (elems.size() -2) ) ? validate() :
  58. 		 	any_of(s_opmap.begin(),s_opmap.end(),[&]( typename op_map::value_type& o ){
  59. 				ops.push_back(o.first);
  60. 				return next_comb() || (ops.pop_back(), false);
  61. 			});
  62. 	}
  63. };
  64.  
  65. template < class num_type >
  66. int main_deleg(){
  67. 	for( string line; getline(cin,line); ){
  68. 		replace (line.begin(), line.end(), ':', ' ');
  69.  
  70. 		istringstream iss(line);
  71. 		vector<num_type> list;
  72.  
  73. 		for( num_type n; ! (iss >> n).fail(); list.push_back(n) );
  74.  
  75. 		if( list.size() > 1 )
  76. 			calculator<num_type>(list).calculate();
  77. 		else
  78. 			cout << line << ": invalid line. skip. " << endl;
  79. 	}
  80. 	return 0;
  81. }
  82.  
  83. int main(){ return main_deleg<double>(); }
  84.  
  85.  
Success #stdin #stdout 0s 3496KB
comments (?)
stdin
copy 
1 1 1 1 : 6
1 2 3 4 5 : 10
1 2 3 4 5 6 7 8 :  10
stdout
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1  1  1  1 has no op-combs to be 6
1 + 2 + 3 * 4 - 5 = 10
1 * 2 * 3 * 4 - 5 + 6 - 7 - 8 = 10
https://ideone.com/wS9HYD
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
secret

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