evaluate-reverse-polish-notation.txt

class Solution {
public:
	void setOperand(stack<int>& s, int& a, int& b)
	{
		a=s.top();
		s.pop();
		b=s.top();
		s.pop();
	}

    int evalRPN(vector<string> &tokens)
	{
		stack<int> s;
		int a,b;
		for(vector<string>::iterator it=tokens.begin();it!=tokens.end();it++)
		{
			if(*it=="+")
			{
				setOperand(s, a, b);
				s.push(b+a);
			}
			else if(*it=="-")
			{
				setOperand(s, a, b);
				s.push(b-a);
			}
			else if(*it=="*")
			{
				setOperand(s, a, b);
				s.push(b*a);
			}
			else if(*it=="/")
			{
				setOperand(s, a, b);
				s.push(b/a);
			}
			else
			{
				s.push(atoi(it->c_str()));
			}
		}
		return s.top();
    }
};