evaluateReversePolishNotation.cpp

class Solution {
public:
    int evalRPN(vector<string>& tokens) {
        stack<int> myStack;
        for(auto str : tokens) {
            if(str != "+" && str != "-" && str != "*" && str != "/") {
                myStack.push(stoi(str));
            }
            else {
                int second = myStack.top(); myStack.pop();
                int first = myStack.top(); myStack.pop();
                int result;
                switch (str[0]) {
                    case '+':{
                        result = first + second;
                        break;
                    }
                    case '-':{
                        result = first - second;
                        break;
                    }
                    case '*':{
                        result = first * second;
                        break;
                    }
                    case '/':{
                        result = first / second;
                        break;
                    }
                    default:{
                        result = 0;
                        break;
                    }
                }
                myStack.push(result);
            }
        }
        return myStack.size() == 1 ? myStack.top() : 0;
    }
};