Evaluate Reverse Polish Notation using a Stack

You can use Stacks to work out RPN. Really.

You might be wondering how to calculate Reverse Polish Notation. You might also be surprised how easy it is when you use a stack.

Read on and find out…

Photo by Lina Verovaya on Unsplash

Difficulty: Beginner | Easy | Normal | Challenging

Prerequisites:

• Some understanding of a stack (guide HERE)
• Some understanding of Reverse Polish Notation (guide HERE)

Terminology

Operand: The value on which an operator is performed

Operator: A symbol like minus that shows an operation

Reverse Polish Notation (RPN): A mathematical notation in which operators follow operands

Stack: A data structure used to store objects

The algorithm

Stacks can be used to evaluate postfix notation equations (also known as Reverse Polish notation).

So the algorithm moves along the expression, pushing each operand on the stack while operators cause two items to be popped off the stack, evaluated and the result pushed back on the stacks.