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  1. #include <iostream>
  2. #include <stack>
  3.  
  4. using namespace std;
  5.  
  6. bool CheckNumber(string str)
  7. {
  8.     int i = 0;
  9.     bool flag = true;
  10.     bool dot = false;
  11.     while (str[i])
  12.     {  
  13.         if (str[i] < 48 || str[i] > 57)
  14.             {
  15.             if (str[i] != '.')
  16.                 return false;
  17.             if (dot && str[i] == '.')
  18.                 return false;
  19.             if (i!=0 && str[i] == '-')
  20.                 return false;
  21.             }
  22.         if (str[i] == '.')
  23.             dot = true;
  24.         ++i;
  25.     }
  26.     return true;
  27. }
  28.  
  29. int main()
  30. {
  31.     string c;
  32.     float a, b;
  33.     stack<float> st;
  34.     bool flag = false; 
  35.     while (cin >> c)
  36.     {
  37.         if (c == "+" || c == "-" || c == "*" || c == "/")
  38.         {
  39.             if (!st.empty())
  40.             {
  41.                 a = st.top();
  42.                 st.pop();
  43.                 if (!st.empty())
  44.                 {
  45.                     b = st.top();
  46.                     st.pop();
  47.                     if (c == "+")
  48.                         st.push(b + a);
  49.                     else if (c == "-")
  50.                         st.push(b - a);
  51.                     else if (c == "*")
  52.                         st.push(b * a);
  53.                     else
  54.                     {
  55.                         if (a != 0)
  56.                             st.push(b / a);
  57.                         else
  58.                             flag = true;
  59.                     }
  60.                 }
  61.                 else
  62.                     flag = true;
  63.             }
  64.             else
  65.                 flag = true;
  66.         }
  67.         else
  68.         {
  69.             if (CheckNumber(c))
  70.                 st.push(stof(c));
  71.             else
  72.                 flag = true;
  73.         }
  74.         if (cin.peek() == 10 )
  75.         {
  76.             if (st.size() == 1 && !flag)
  77.                 printf("%.4f\n", st.top());
  78.             else
  79.                 cout << "ERROR" << endl;
  80.             while (!st.empty())
  81.                 st.pop();
  82.             flag = false;
  83.         }
  84.     }
  85.     if (st.size() == 1 && !flag)
  86.         printf("%.4f\n", st.top());
  87.     else
  88.         cout << "ERROR" << endl;
  89.     while (!st.empty())
  90.         st.pop();
  91.     return 0;
  92. }
Success #stdin #stdout 0s 15240KB
comments (?)
stdin
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1 2 3 /
2 3 /
3 4 * /
1 2 4 + - 5 * 7 /
stdout
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ERROR
0.6667
ERROR
-3.5714
https://ideone.com/S2Bk7T
language:
C++ (gcc 8.3)
created:
5 years ago
visibility:
public

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