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  1. #include <algorithm>
  2. #include <vector>
  3. #include <functional>
  4. #include <iostream>
  5.  
  6. template <typename T> struct Term
  7. {
  8.     Term() : coeff(), exponent(0) { }
  9.     Term(T c, int e) : coeff(c), exponent(e) { }
  10.     T coeff;
  11.     int exponent;
  12. };
  13.  
  14. template <typename T> struct Poly
  15. {
  16.     typedef Term<T> term_t;
  17.     typedef std::vector<term_t> terms_t;
  18.     terms_t _terms;
  19.  
  20.     Poly(terms_t terms) : _terms(terms) { }
  21.  
  22.     void combineLikeTerms()
  23.     {
  24.         if (_terms.empty())
  25.             return;
  26.  
  27.         std::sort(_terms.begin(), _terms.end(), order);
  28.  
  29.         term_t accum(T(), 0);
  30.         std::vector<term_t> result;
  31.  
  32.         for (typename terms_t::const_iterator curr = _terms.begin(); curr!= _terms.end(); ++curr)
  33.         {
  34.             if (curr->exponent == accum.exponent)
  35.                 accum.coeff += curr->coeff;
  36.             else
  37.             {
  38.                 if (accum.coeff != 0)
  39.                     result.push_back(accum);
  40.                 accum = *curr;
  41.             }
  42.         }        
  43.         if (accum.coeff != 0)
  44.             result.push_back(accum);
  45.  
  46.         std::swap(_terms, result); // only update if no exception
  47.     }
  48.  
  49.   private: 
  50.     static bool order(term_t const& a, term_t const& b)
  51.         { return a.exponent > b.exponent; }
  52. };
  53.  
  54. int main()
  55. {
  56.     Poly<int>::terms_t terms;
  57.     terms.push_back(Term<int>( 4, 1 ));
  58.     terms.push_back(Term<int>( 6, 7 ));
  59.     terms.push_back(Term<int>(-3, 1 ));
  60.     terms.push_back(Term<int>( 5, 5 ));
  61.  
  62.     Poly<int> demo(terms);
  63.  
  64.     typedef std::vector<Term<int> >::const_iterator It;
  65.  
  66.     demo.combineLikeTerms();
  67.  
  68.     for (It it = demo._terms.begin(); it!= demo._terms.end(); ++it)
  69.         std::cout << (it->coeff>0? " +" : " ") << it->coeff << "x^" << it->exponent;
  70.  
  71.     std::cout << "\n";
  72. }
Success #stdin #stdout 0.01s 2816KB
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Standard input is empty
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 +6x^7 +5x^5 +1x^1
https://ideone.com/aHuB8
language:
C++ (gcc 8.3)
created:
11 years ago
visibility:
secret

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