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  1. #include <iostream>
  2. #include <sstream>
  3. #include <iterator>
  4.  
  5. #include <vector>
  6. #include <string>
  7. #include <stack>
  8. #include <map>
  9. #include <functional>
  10.  
  11. using namespace std;
  12.  
  13. int compute(int a, int b, string op)
  14. {
  15. 	static map<string,function<int(int,int)> >  operations;
  16. 	operations["+"] = plus<int>();
  17. 	operations["-"] = minus<int>();
  18. 	operations["*"] = multiplies<int>();
  19. 	operations["/"] = divides<int>();
  20.  
  21. 	return operations[op](b,a);
  22. }
  23.  
  24. int evalRPN(vector<string>& tokens) 
  25. {
  26.     int n = tokens.size();
  27.     if (n == 0)
  28.         return 0;
  29.     stack<int> S;
  30.     int a, b;
  31.     for (int i = 0; i < n; i++)
  32.     {
  33.     	string operators = "+-*/";
  34.         string tmp = tokens[i];
  35.         if (operators.find(tmp) != string::npos) // <== [1]
  36.         {
  37.             a = S.top(); S.pop();
  38.             b = S.top(); S.pop();
  39.             S.push(compute(a, b, tmp));
  40.         }
  41.         else
  42.         {
  43.             S.push(stoi(tmp));
  44.         }
  45.     }
  46.     return S.top();
  47. }
  48.  
  49. int main() {
  50. 	vector<string> input;
  51. 	string tmp;
  52. 	getline(cin,tmp);
  53. 	istringstream istst(tmp);
  54.  
  55. 	copy(istream_iterator<string>(istst),
  56.      istream_iterator<string>(),
  57.      back_inserter(input));
  58.  
  59. 	cout << evalRPN(input);
  60. 	return 0;
  61. }
Success #stdin #stdout 0s 3432KB
comments (?)
stdin 
33 9 - 5 3 + /
stdout 
3
https://ideone.com/wSl5zQ
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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