Answered step by step
Verified Expert Solution
Link Copied!

Question

1 Approved Answer

Python Issue Postfix notation (also known as Reverse Polish Notation or RPN in short) is a mathematical notation in which operators follow all of its

Python Issue

Postfix notation (also known as Reverse Polish Notation or RPN in short) is a mathematical notation in which operators follow all of its operands. It is different from infix notation in which operators are placed between its operands.

The algorithm to evaluate any postfix expression is based on stack and is pretty simple:

Initialize empty stack

For every token in the postfix expression (scanned from left to right):

If the token is an operand (number), push it on the stack

Otherwise, if the token is an operator (or function):

Check if the stack contains the sufficient number of values (usually two) for given operator

If there are not enough values, finish the algorithm with an error

Pop the appropriate number of values from the stack

Evaluate the operator using the popped values and push the single result on the stack

Return the final result of the calculation

Implement a function def eval_postfix(expression_str) that evaluates and returns the result of a postfix expression. The postfix expression to be evaluated is passed to the function as a string parameter. Each component of the postfix expression string is separated by a single space. Your function needs to support the following operations: "+", "-", "*", "/", "%" and "**". Your function should also work with values consisting of more than one digit.

For example:

Test Result
print(eval_postfix("2 3 * 4 +"))
10
print(eval_postfix("2 3 4 + *"))
14

Step by Step Solution

There are 3 Steps involved in it

Step: 1

blur-text-image

Get Instant Access to Expert-Tailored Solutions

See step-by-step solutions with expert insights and AI powered tools for academic success

Step: 2

blur-text-image

Step: 3

blur-text-image

Ace Your Homework with AI

Get the answers you need in no time with our AI-driven, step-by-step assistance

Get Started

Recommended Textbook for

XML Data Management Native XML And XML Enabled Database Systems

Authors: Akmal Chaudhri, Awais Rashid, Roberto Zicari, John Fuller

1st Edition

ISBN: 0201844524, 978-0201844528

More Books

Students also viewed these Databases questions

Question

2. What do you believe is at the root of the problem?

Answered: 1 week ago