Lintcode-medium-evaluate Reverse Polish Notation

Evaluate the value of an arithmetic expression inreverse Polish Notation.

Valid operators is + , - , * , / . Each operand is an integer or another expression.

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

 Public classSolution {/**     * @paramtokens the Reverse Polish Notation *@returnThe value*/     Public intEVALRPN (string[] tokens) {//Write Your code here                if(Tokens = =NULL|| Tokens.length = = 0)            return0; Stack<Integer> stack =NewStack<integer>();  for(inti = 0; i < tokens.length; i++){            if(!isOp (Tokens[i]))            {Stack.push (Integer.parseint (tokens[i])); }            Else{                intnum2 =Stack.pop (); intNUM1 =Stack.pop (); if(Tokens[i].equals ("+")) Stack.push (Num1+num2); Else if(Tokens[i].equals ("-")) Stack.push (Num1-num2); Else if(Tokens[i].equals ("*")) Stack.push (Num1*num2); ElseStack.push (Num1/num2); }        }                returnStack.pop (); }         Public BooleanisOp (String str) {return(Str.equals ("+") | | str.equals ("-") | | str.equals ("*") | | str.equals ("/")); }}

Lintcode-medium-evaluate Reverse Polish Notation