150. Evaluate Reverse Polish Notation

int evalRPN(vector<string>& tokens) {
vector<int> memo;
int res=0;
for(auto i:tokens){
int temp=0;
if(i=="+"||i=="-"||i=="*"||i=="/"){
int second = memo.back();
memo.pop_back();
int first = memo.back();
memo.pop_back();
if(i=="+")
memo.push_back(first+second);
else if(i=="-")
memo.push_back(first-second);
else if(i=="*")
memo.push_back(first*second);
else if(i=="/"){
memo.push_back(first/second);
}
}
else
memo.push_back(stoi(i));
}
return memo.back();
}