Evaluate Reverse Polish Notation questioneditorial Solution

Evaluate the value of an arithmetic expression in Reverse Polish Notation.

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

Some Examples:

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



Stack only saves numbers, encounters operator, pops two numbers, calculates them, and then deposits the results in a stack. The first element of the last stack is the answer.
Note-the difference from/to the first pop value is on the right side of the operator.

 Public intEVALRPN (string[] tokens) {Stack<int> stack =Newstack<int>();  for(inti =0;i< tokens. Count (); i++)        {            if(Tokens[i] = ="+") {stack. Push (Stack. Pop ()+stack.            Pop ()); }            Else if(Tokens[i] = ="-") {stack. Push (-1*stack. Pop () +stack.            Pop ()); }            Else if(Tokens[i] = ="*") {stack. Push (Stack. Pop ()*stack.            Pop ()); }            Else if(Tokens[i] = ="/")            {                intA =stack.                Pop (); intb =stack.                                Pop (); Stack. Push (b/a); }            Else{stack.            Push (Int32.Parse (tokens[i)); }        }        returnstack.    Peek (); }

Evaluate Reverse Polish Notation questioneditorial Solution