Leetcode: eva luate Reverse Polish Notation

eva luate the value of an arithmetic expression in Reverse Polish Notation.

Valid operators are +, -, *, /. Each operand may be an integer or another expression.

Some examples:

  ["2", "1", "+", "3", "*"] -> ((2 + 1) * 3) -> 9
  ["4", "13", "5", "/", "+"] -> (4 + (13 / 5)) -> 6

int eva lRPN(vector
  
    &tokens) {
        // IMPORTANT: Please reset any member data you declared, as
        // the same Solution instance will be reused for each test case.
        if(tokens.size()==1)return stoi(*tokens.begin());
        stack
   
     numbers; vector
    
     ::iterator it = tokens.begin(); int op1 = 0; int op2 = 0; while(it != tokens.end()) { if(*it == "+"||*it == "-" || *it == "*" || *it == "/") { op2 = numbers.top(); numbers.pop(); op1 = numbers.top(); numbers.pop(); if(*it == "+") numbers.push(op1+op2); else if(*it == "-") numbers.push(op1-op2); else if(*it == "*") numbers.push(op1*op2); else numbers.push(op1/op2); } else numbers.push(stoi(*it)); it++; } return numbers.top(); }