A calculator that will evaluate a prefix expression (Polish Notation) and show the step-by-step process used to arrive at the result using stack.
A "Prefix Expressions" is a expression in which first operator comes and preceded by strings. Every prefix string longer than a single variable contains first and second operands followed by an operator.
The main advantage of this format is that it does not require parentheses for any ambiguous expression.
| Infix notation | Prefix notation |
|---|---|
| 3 + 4 | + 3 4 |
| 3 - (4 * 5) | - 3 * 4 5 |
| (3 + 4) * 5 | * + 3 4 5 |
| (3 - 4) / (5 + 2) | / - 3 4 + 5 2 |
In the code provided, the app/calculator.js file exports a calculate function. This function is expected to take an Prefix expression as a string, and output the numerical solution.
To run the code:
npm install # install dependencies npm start # use the calculator with an interactive prompt npm test # run the tests