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  1. #include <iostream>
  2. #include <vector>
  3. #include <sstream>
  4. #include <algorithm>
  5.  
  6. using namespace std;
  7.  
  8. string to_string(const vector<int>& poly)
  9. {
  10.   ostringstream os;
  11.   size_t deg = poly.size();
  12.  
  13.   if(deg > 2)
  14.   {
  15.     --deg;
  16.     os << poly[deg] << "x^" << deg;
  17.   }
  18.  
  19.   os.setf(ios_base::showpos);
  20.  
  21.   while(deg-- > 2)
  22.   {
  23.     os << poly[deg] << "x^" << deg;
  24.   }
  25.  
  26.   os << poly[deg--] << "x";
  27.   os << poly[deg];
  28.  
  29.   return os.str();
  30. }
  31.  
  32. vector<int> from_string(const string& str)
  33. {
  34.   istringstream is(str);
  35.   vector<int> result;
  36.   char c;
  37.   int x = 0;
  38.   while(is.get(c))
  39.   {
  40.     switch(c)
  41.     {
  42.       case '+':
  43.       case '-':
  44.         is.putback(c);
  45.         is >> x;
  46.         result.push_back(x);
  47.       break;
  48.       case '^':
  49.         is >> x;
  50.       break;
  51.       default:
  52.         if(isdigit(c))
  53.         {
  54.           is.putback(c);
  55.           is >> x;
  56.           result.push_back(x);
  57.         }
  58.       break;
  59.     }
  60.   }
  61.   reverse(result.begin(), result.end());
  62.   return result;
  63. }
  64.  
  65. int main()
  66. {
  67.   vector<int> koef = {5, -5, 3};
  68.   string s = to_string(koef);
  69.  
  70.   cout << s << endl;
  71.  
  72.   vector<int> result = from_string(s);
  73.  
  74.   for(int i : result)
  75.   {
  76.     cout << i << " ";
  77.   }
  78. }
Success #stdin #stdout 0s 15240KB
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stdin
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Standard input is empty
stdout
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3x^2-5x+5
5 -5 3
https://ideone.com/qGEGsj
language:
C++ (gcc 8.3)
created:
4 years ago
visibility:
public

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